A range of major players interested in acquiring all or a large piece of Yahoo have been prepping possible bids and have been in touch with the Internet giant’s board over the last several days.

While Yahoo has publicly said it was not for sale, according to numerous sources both inside and outside the company, it has been receptive to the interest and its Chairman Roy Bostock and Co-founder Jerry Yang have spoken to several.

Among the possible players: Silicon Valley venture firm Andreessen Horowitz, which is working with private equity firm Silver Lake, in a deal that also might include Russia’s DST Global and Yahoo’s Japanese partner Masa Son; former News Corp. exec Peter Chernin, who is partnered with Providence Equity Partners; and the possibility that Yahoo’s Chinese partner, Alibaba Group, might consider entering the fray in what could be a reverse merger of sorts.

Also being rung up by some of the parties: Microsoft — Yahoo’s advertising and search partner — which is being seen as a possibly moneybags in any deal.

The movement among these investors is against a backdrop of increasing pressure for Yahoo’s board, after it fired CEO Carol Bartz last week. In the wake of the dramatic move, shareholders have upped criticism of Bostock and the board and have been looking hard for alternatives.

Today, that included hedge fund investor Daniel Loeb of Third Point, which has a 5.1 percent stake in Yahoo. In a filing this morning, he said he might increase that amount, and described a testy hour-long phone call he had earlier this week with Bostock that ended abruptly with a hang-up from Yahoo.

Sources said Loeb called Bostock a “fool,” among other not-so-nice names, on the call and asked for Yang’s help in dumping him.

This comes as exactly no surprise, given his previously strong letter in which Loeb called for Bostock’s ouster.

Loeb has been calling out Bostock — who is also on the boards of Morgan Stanley and Delta Airlines — for a series of gaffes at Yahoo since he became chairman in 2008 (he’s been on the board since 2003).

Those have included: Yahoo’s bungled effort to stave off a takeover by Microsoft several years ago; the too-long enthusiasm for Bartz, who was hired in early 2009 and fired last week; sitting unusually still as competitors such as Facebook, Google and more have out-innovated and outgrown Yahoo; and, of course, the falling knife of a stock, which has dropped precipitously since Bostock has been in charge of the board.

As Loeb wrote in a letter he sent to the company last week:

“It is time that certain members of this Board were held accountable for its past failures and their individual roles. Accordingly, we insist that Mr. Bostock, who championed Ms. Bartz’s hiring and led the charge against the Microsoft deal, promptly resign from the Board.”

Loeb is likely to add to that later today at a high-profile investor conference in New York, where the colorful but tough-talking investor is sure to add more logs to the fire.

But it not only him. Other major shareholders of Yahoo are also in touch with possible outside buyers, seeking a change at the long-troubled company, after its shares have remained in the doldrums, its attrition rate of employees has spiked and its product pipeline has slowed to drip.

This has all been taking place — of course — during one of tech biggest and most innovative booms, in which Yahoo competitors have grown strongly.

Enter Marc Andreessen, the well-known entrepreneur who has transformed himself into one of Silicon Valley’s most powerful venture capitalists.

He and his partner Ben Horowitz recently pulled off another similar deal — with Silver Lake — to take control of a then-troubled Skype. They later flipped it to Microsoft for a large return.

Sources familiar with the situation said the pair have become increasingly intrigued by the situation at Yahoo and believe that its assets and brand are still strong, despite its management turmoil in recent years.

One problem is the huge cost of almost any kind of takeover and also the complexity, given much of Yahoo’s $18.5 billion valuation is due to its Asian assets.

The sale of those shares, as well as the selling off of some of Yahoo’s less core properties, makes for a very complicated situation for anyone.

Said one person looking at the company: “It is one of the more massive hairballs around.”

That is a common sentiment among many of those looking at Yahoo, which has hired Allen & Co. to manage the process.

Also of worry is a bid that would include too many players. Yahoo has long been plagued by indecisiveness on the part of its execs and, mostly, its board.

But one thing all the possible buyers of Yahoo, as well as an increasing number of its shareholders, agree on: The Yahoo board needs a major shake-up.

As Loeb wrote last week, which many I interviewed also echoed:

“This letter details our principled demands for sweeping changes in both the Board of Directors (the “Board”) and Company leadership, and outlines the hidden value of Yahoo, which has been severely damaged — but not irreparably — by poor management and governance.”

Three of Silicon Valley’s more prominent venture firms — Khosla Ventures, Redpoint Ventures and the Founders Fund — are nearing the closing of new funds that will total almost $2 billion.

This despite a bad economy, turbulent markets and lackluster venture returns of late. That said, limited partners looking for an investment edge apparently seem to still be adding more dough to the VC kitty.

Sources familiar with the fundings, in fact, said the raises have been much easier than previous ones.

Khosla has raised almost $2.4 billion since 2009, including $1.3 billion in 2010. Its fourth is now nearly completed, at just under that, which the firm had previously signaled in regulatory filings it planned to raise.

The third fund has been spent on cleantech companies, but also on early-stage high-profile Internet start-ups such as Square.

Redpoint will focus its fund — which sources said was $400 million — on growth opportunities.

Its last fund in 2010 was $400 million, too. It has invested that money in start-ups, such as Jumptap, Kabam and Pure Storage.

Lastly, the Founders Fund — with high-profile partners Peter Thiel and Sean Parker — is aiming at a $350 million fund with a $150 million “cushion” to raise more. Its last fund of $250 million was raised last year.

Founders Fund has recently made investments in Path, Azumio and Topsy.

But Sittig is now back at the mother ship, having rejoined in January with the title “product architect,” as Kim-Mai Cutler at Inside Facebook reported Friday.

This comes at a time when Facebook has more than 2,000 employees, plans to move to a corporate campus within the next year and says an IPO is likely in 2012. It’s a lot different from when Sittig first joined in 2005.

Sittig had been away from the company only six months before accepting an offer to return. He told NetworkEffect that he felt the outside world lacked the “scale and ambition” of Facebook. Plus, he was lured by some of Facebook’s recent hires: Sam Lessin and Justin Shaffer, brought in through the acquisitions of their companies Drop.io and Hot Potato, respectively (both of which occurred while Sittig was away).

Here’s Sittig’s explanation:

I left Facebook last June because I’d been there for five years and wanted to see what else I could apply myself to. I didn’t expect at the time that I’d head back.

I spent my time off advising companies and looking for new ideas. But for each idea I wanted to build myself, I kept realizing that Facebook was the only place with the scale and ambition where I could build my ideas successfully.

So that, combined with the steady influx of talented people like Sam Lessin and Justin Shaffer, convinced me to say yes when I was approached with an offer to rejoin.

Prior to Facebook, Sittig worked at Napster, after it bought the Mac client Macster that he had helped develop. He studied philosophy at UC Berkeley. Sittig has made angel investments in companies such as Hearsay, which makes corporate social media management tools.

Please see the disclosure about Facebook in my ethics statement.

Bob Pittman’s Pilot Group, an early backer of Mark Pincus’s company, has sold the majority of its Zynga shares. I don’t have details on the size of Pilot’s stake or the value of the transaction, but it’s going to be a huge return by any measure.

Pittman, guided by his digital deal guy, Andy Russell, got in on Zynga’s $10 million A round in January 2008. Since then, Zynga has raised an astonishing $350 million, all while claiming it doesn’t need the money. Investors love the story and are reportedly valuing the company at $3 billion in secondary market deals.

If Zynga’s future is so bright, why sell now? No comment from Zynga or Pilot. But a person familiar with the transaction tells me Pilot is reinvesting its profits in another deal. And it continues to hold some Zynga shares.

So if this thing keeps going–bankers see Zynga as one of the most likely big-name tech IPO candidates in the next couple years–Pilot will still see more upside.

Now this is just getting silly.

Pali Research says sales of the Palm Pre are slowing. RBC’s Mike Abramsky says they aren’t and claims 325,000 to 375,000 have been sold to date, ahead of his expectations.

Citing some decidedly unscientific poll data, Jesup and Lamont analyst Kevin Dede suggests the device is plagued by build-quality issues and a high exchange/return rate, potentially 40 percent. Abramsky says it’s between two and three percent and calls BS on the build-quality issue.

“Most buyers appear delighted with their new Pre user experience,” Abramsky said in a research note Friday. “Pre satisfaction appears higher than legacy Palm devices (e.g., Treo), affirming improved execution from the ‘New’ Palm, including engineering, manufacturing, quality and process improvements.”

So, Pre sales are slowing. Or, they’re not.

And exchange/return rates are high.

Unless they’re not.

And these analysts are on point.

Unless, of course, they’re not. Too bad it’s impossible to tell without official numbers from Palm (PALM) or Sprint (S).

Clearly, the so-called IPO window has been slammed shut by the capital crisis. Indeed, data from Dealogic show that 298 IPOs were postponed or withdrawn over the past 11 months–quite a few more than the 167 that met that fate in all of the 2007. And those companies that went through with their offerings didn’t fare so well. Almost 50 percent of new issues fell on their first day of trading, and aftermarket performance was poor, according to Renaissance Capital; the average new issue was down 38 percent by year-end.

“Performance of 2008 new issues in the US was abysmal by historical standards, although not surprising given the steep decline in equities,” says Renaissance. “The average first day pop was a paltry 2%, down from the more than 10% average first day return investors became accustomed to in each of the last five years. A whopping 58% of all new issues traded down in their market debut, the worst first day showing in at least a decade and almost four times the IPO market’s 10-year average.”

Little wonder, then, that the U.S. went three months without an IPO during the second half of the year–the longest dry spell since the recession of the 1970s.

When will the IPO market return? Tough to say. Renaissance says there’s a lot of pent-up demand by potential issuers to raise equity capital. But they’re not likely to test the IPO waters until the financial markets stabilize.