Microsoft–furious over a recent talent grab of its top advertising exec by Facebook–has been considering a wide range of options, including legal action to block the move, according to sources close to the situation.

Lawyer at both companies have been in back-and-forth talks in recent days after the hiring of Microsoft’s global ad sales head Carolyn Everson by the Silicon Valley social networking powerhouse to be its VP of global sales.

Among the more likely solutions being discussed: Barring Everson–a longtime ad sales exec who came to Microsoft from MTV Networks–from using any strategic information she learned at the company and also from contacting certain ad clients on behalf of Facebook for a certain period of time.

While a legal action to stop her from actually taking the position is the most serious option, it is certainly not without precedent for Microsoft. The company recently got a temporary restraining order to block one of its top government relations execs, Matt Miszewski, from working at Salesforce.com, pointing to non-compete and confidentiality contracts.

Whatever happens, it is clear the Everson hiring has infuriated Microsoft execs, especially CEO Steve Ballmer, since the company regards Facebook as a close partner. Microsoft is also a longtime investor in Facebook.

While considering a temporary restraining order against Everson in this kind of situation–since it is essentially the same job–is standard operating procedure for any company, several sources said tensions are higher than usual.

“This is just tone deaf on Facebook’s part not to think this would not be a problem,” said one person.

One particularly irksome aspect–top Facebook execs did not call Ballmer before news of the appointment leaked out to assuage the situation.

Facebook COO Sheryl Sandberg did release a statement when BoomTown broke news of the move in mid-February, in an attempt to make nice.

“Microsoft was one of our earliest partners and is still one of our most valued,” she said, in part. “We look forward to continuing to expand our relationship with them.”

Her dulcet words have apparently not worked.

In fact, the talent raid came as a surprise to many at Microsoft, especially since Everson (pictured here) had been hired in June after a long search and had become a high-profile presence at internal and external Microsoft events.

That included organizing the splashy “Imagine 2011, Microsoft Advertising’s Marketing Leadership Summit.” The event is set to take place at the end of March at the software giant’s Redmond, Wa. HQ and will include an evening concert by the band Train.

Now she will be doing such things for Facebook, where Everson will be replacing longtime and well-regarded ad exec Mike Murphy, who left the Palo Alto, Calif., company last fall. She will report to former Googler David Fischer, VP of Advertising and Global Operations.

Having a top exec who is amenable to and well known by Madison Avenue is key for Facebook as it ramps up its business, in anticipation of an IPO next year.

Despite being private, Facebook has recently been valued at between $50 and $60 billion by investors, who have been eagerly buying up shares of the company on secondary markets.

Under Murphy and Fischer, ad sales have been doing well already. Facebook’s share of online display advertising has more than quadrupled, from about three percent to almost 14 percent of the nearly $9 billion U.S. market, according to a recent survey.

In growing so quickly, Facebook has grabbed ad revenue–reportedly $2 billion last year–from old online powerhouses, especially Yahoo, Microsoft and AOL, and is also in a big fight with Google over premium ad sales.

Facebook’s surging usage and engagement are the reasons for the increased interest from advertisers, as well as its global growth in both market share and mindshare of consumers.

The opportunity at Facebook is clearly a big–and probably irresistible–move for the dynamic Everson, who has mostly worked in the mainstream media for much of her career.

Still, while movement of execs among top tech companies is not uncommon, there has been a lot less from Microsoft to Facebook.

Instead, Facebook has been most aggressive in its efforts to attract talent from Google.

No longer. In fact, the week before Facebook grabbed Everson, it also hired an up-and-coming exec, Chris Daniels, GM of Bing Mobile Product Management, to be its director of business development.

Still, there is some hiring war history between the companies. In late 2008, Microsoft’s Ballmer managed to lure former Yahoo exec Qi Lu to run its Online Services Division, several sources at both companies said, after he had told Facebook he would work there as its engineering lead. Lu had also been heavily recruited by Google.

Eventually, that was water under the bridge, which is what Facebook is hoping will happen with Microsoft over Everson.

Also important in the weighing of options at Microsoft is the obvious importance of keeping up good relations with Facebook. It is an important partnership, especially for its Bing search business, as an advantage over Google.

“Everyone is hoping to resolve this amicably,” said one person close to the situation. “There has been some damage to the relationship for sure, but the question is whether Microsoft wants to do something that would escalate that damage.”

Not surprisingly, both Facebook and Microsoft declined to comment on the fracas.

Nortel Networks has rejected Research In Motion’s bid for the wireless infrastructure assets Nortel is unloading as part of bankruptcy proceedings. RIM said Monday night that it intended to offer $1.1 billion for Nortel’s CDMA and LTE businesses, but was told it could do so only if it agreed not to bid on other Nortel assets, something it had intended to do.

In a blistering statement, RIM (RIMM) accused Nortel (NT) of imposing unfair conditions on the court-supervised auction of its assets and of jeopardizing their continued Canadian ownership.

“RIM is extremely disappointed that Nortel’s world leading technology, the development of which has been funded in part by Canadian taxpayers, seems destined to leave Canada,” said co-CEO Jim Balsillie. “RIM remains extremely interested in acquiring Nortel assets through a Canadian ownership solution that would serve the dual purpose of keeping key wireless technologies in Canada and extending RIM’s leadership in the research, development and distribution of leading edge wireless solutions, but RIM has found itself blocked at every turn.”

Why? Nortel says RIM was late to the game and hasn’t followed proper auction procedure.

“Other parties moved expeditiously to comply with the court approved procedures to become a qualified bidder,” the company said in a statement. “It was not until July 15, 2009, that RIM submitted a letter to Nortel asking to be a qualified bidder and since that time, Nortel has diligently attempted to work with RIM on acceptable confidentiality terms relating to Nortel’s valuable intellectual property assets, but RIM refused to comply with the court approved procedures.”

What’s really going on here? It’s hard to say, though clearly there’s more to the story. After all, RIM’s $1.1 billion bid is far, far more than Nokia Siemens’s stalking horse bid of $650 million. And what does RIM want with the CDMA business, anyway?

This morning, EMC raised its offer for Data Domain to $2.1 billion from $1.8 billion, an 11 percent increase over its previous all-cash bid. Data Domain’s board had previously recommended that shareholders reject EMC’s $30-a-share cash bid in favor of a $30 cash-and-stock offer from NetApp (NTAP).

Hard to see the board doing so again now that the EMC (EMC) has sweetened the financial end of its proposal and removed some deal-protection provisions with which Data Domain (DDUP) had taken issue. With those gone, EMC’s bid is clearly superior to NetApp’s, CEO Joe Tucci claims, and it would be hard to argue otherwise.

“Over the past several weeks we’ve received strong support from many Data Domain stockholders and customers, validating our belief that EMC is Data Domain’s best choice,” Tucci wrote in a letter to Data Domain’s leadership. “With regulatory requirements now fulfilled, and in light of the clearly superior proposal we submitted to Data Domain’s Board of Directors today, we expect Data Domain to sign our definitive agreement that will deliver superior value in cash to the Data Domain stockholders in as little as two weeks.”

Data Domain has until midnight on July 17 to accept the offer.

UPDATE: NetApp responded to EMC’s announcement with the following statement:

“In response to EMC’s revised, unsolicited offer, the NetApp Board of Directors will carefully weigh its options, keeping in mind both its fiduciary duty to its stockholders and its disciplined acquisition strategy. We will provide an update shortly.”

This morning, EMC raised its offer for Data Domain to $2.1 billion from $1.8 billion, an 11 percent increase over its previous all-cash bid. Data Domain’s board had previously recommended that shareholders reject EMC’s $30-a-share cash bid in favor of a $30 cash-and-stock offer from NetApp (NTAP).

Hard to see the board doing so again now that the EMC (EMC) has sweetened the financial end of its proposal and removed some deal-protection provisions with which Data Domain (DDUP) had taken issue. With those gone, EMC’s bid is clearly superior to NetApp’s, CEO Joe Tucci claims, and it would be hard to argue otherwise.

“Over the past several weeks we’ve received strong support from many Data Domain stockholders and customers, validating our belief that EMC is Data Domain’s best choice,” Tucci wrote in a letter to Data Domain’s leadership. “With regulatory requirements now fulfilled, and in light of the clearly superior proposal we submitted to Data Domain’s Board of Directors today, we expect Data Domain to sign our definitive agreement that will deliver superior value in cash to the Data Domain stockholders in as little as two weeks.”

Data Domain has until midnight on July 17 to accept the offer.

UPDATE: NetApp responded to EMC’s announcement with the following statement:

“In response to EMC’s revised, unsolicited offer, the NetApp Board of Directors will carefully weigh its options, keeping in mind both its fiduciary duty to its stockholders and its disciplined acquisition strategy. We will provide an update shortly.”

On Monday the company once again said its bid for the data storage equipment maker Data Domain is “superior” to a competing offer from NetApp. This, despite the fact that Data Domain earlier in the day issued a statement recommending that shareholders reject EMC’s $30-a-share cash bid and instead accept a $30 cash-and-stock offer from NetApp.

“Our Board is committed to enhancing stockholder value and, after careful review with our outside advisors, determined that the $30 per share EMC Offer is not in the best interests of our stockholders at this time,” said Frank Slootman, president and CEO of Data Domain.

Why not? Well, among other things Data Domain hasn’t been able to discuss EMC’s offer because EMC hasn’t yet accepted the confidentiality and standstill agreement that would allow it to do so. For another, Data Domain must pay a $57 million termination fee if it should abandon its deal with NetApp–and that’s on top of a host of other considerable transaction expenses.

That’s understandable, I suppose. Still, it’s difficult to see why Data Domain insists that EMC’s all-cash offer is worth less than NetApp’s cash-and-paper bid. Unless it’s doing so to force EMC’s hand deeper into its wallet. And, indeed, that may be exactly what’s happening here. Sources say. EMC (EMC) could raise its offer to as much as $35 per share to win Data Domain (DDUP) or force NetApp (NTAP) to pay more than it can afford for it. “EMC is in the win-win box and NetApp is in the lose-lose box,” a source close to the company told Reuters. “EMC can pay more than NetApp can in a reasonable range. If NetApp wants to pay at an unreasonable range, that’s good for EMC.”