Microsoft Corporation (NASDAQ: MSFT) has been hungry for online advertising companies lately. Of course, the latest deal was a zinger: $6 billion for aQuantive (NASDAQ: AQNT).

In light of all this, it seems natural that Mr. Softy would buy Yahoo! Inc. (NASDAQ: YHOO). But Microsoft's chief advertising strategist, Yusuf Mehdi, threw cold water on this and said "[w]e have all of the pieces we need to move forward.''

What to make of this? I had a chance to interview Allan B. Krans, who is an analyst with Technology Business Research (TBR). According to him:

"I agree with the statement that Microsoft has all of the tools needed to be successful in the online business. However, a solid toolset alone will not spur an improvement in Microsoft's online business. Microsoft needs to drive online search traffic in order to attract advertisers to its toolset. For this reason, we believe a merger/acquisition with Yahoo! continues to make sense for Microsoft. Combining the two companies' respective shares of the online search market gives Microsoft the opportunity to drive search traffic and leverage its newly compiled advertising toolset."

I also got this from John Byrne, who is also an analyst with TBR:

"At this point I think maybe Yahoo is the stickler though - they've just implemented Project Panama and they probably feel like they're going to show real improvement over the next few quarters which would increase their value without an acquisition. Then maybe next year they're in a much stronger position."

Tom Taulli is the author of various books, including the Complete M&A Handbook and the EDGAR-Online Guide to Decoding Financial Statements.