• Week ending June 6: 3.43 percent
• Week ending June 13: 4.57 percent
• Week ending June 20: 5.35 percent
• Week ending June 27: 6.63 percent

“Looking at the weekly percentage of U.S. searches for Bing, the search engine has grown at an average weekly rate of 25 percent for the month of June 2009,” Hitwise explains. “Adding in Live.com and MSN Search along with Bing, the combined search engines have grown at an average of 16 percent during June 2009. Bing grew faster than the three other prominent search engines for the month.”

Impressive. But sadly, not enough for Microsoft (MSFT) to make real headway. Because Bing actually ended up losing market share during June, slipping to 5.25 percent from the 5.64 percent it had in May (click on chart below). Meanwhile, Google (GOOG) gained share, rising to 74.04 percent from 73.66 percent in May. And Yahoo (YHOO) gained as well, starting out the month with a 15.55 percent share and ending it with 16.19 percent.

Reports claim that Microsoft Live Search, once known as Windows Live Search and, prior to that as MSN Search, will henceforth be known as…

Bing.

Which is pretty much what we’ve expected all along. Just what form Bing will take is another matter entirely. Will it simply be Live Search updated and recast? Or will it involve something more? Like perhaps that long-rumored deal with Yahoo (YHOO) BoomTown’s been talking about? Or what if, ZDNet’s Mary Jo Foley speculates, “Microsoft and Yahoo announce some kind of jointly-managed company that will trade ad sales for search engine placement. This ‘MicroHoo’ won’t be a merged Microsoft-Yahoo. Instead it will be some kind of ad/search entity.” What if, indeed. We may find out later this week.

UPDATE: Interesting. ZDNet’s Larry Dignan points to a report from Jeffries analyst Katherine Egbert that suggests Microsoft is indeed preparing for some sort of joint venture or acquisition. A quick excerpt:

“It’s also possible that Microsoft could debut a partnership or make an acquisition of some type that will bolster its online search presence. The software giant registered an LLC Corp. in Delaware last week, a move often made in advance of acquisitions or joint ventures. The registration gave rise to widespread speculation that Microsoft would acquire Citrix since the name of the LLC is somewhat similar to Microsoft’s code name for Citrix. While that’s possible, the timing of the registration and recent debt raise indicate that it might be more likely Microsoft uses the LLC to form a partnership that will boost the amount of traffic flowing through its search engine, perhaps through a partnership with Yahoo! or others.”