Given Microsoft's long pursuit of Yahoo, why was this the right time to bring the overture out in the open? There are several factors and theories, but let's start with a bit of history.

Microsoft CEO Steve Ballmer said in a conference call with six top Wall Street analysts this morning that "we have been engaged in conversations with Yahoo management off and on for the last 18 months. Last night I called [Yahoo CEO] Jerry Yang to discuss our proposal." (Transcript of the call is here: 12-page PDF.) He continued:

"A year ago, the Yahoo management team told us it wasn't really the right time to discuss an acquisition. We believed then in the benefits of combining the two companies, and we believe now in those benefits more than ever. That's why we're making it public today, so both sets of shareholders, employees, and customers can understand the incredible opportunity in the combination of Microsoft and Yahoo."

Some other thoughts on the timing of what is currently an unsolicited offer for Yahoo. (A quick aside: If Yahoo's board, which pledged to consider the offer "carefully and promptly," decides to reject the bid and Microsoft carries forward with it, it would then become a hostile takeover attempt.)

Matt Rosoff, an analyst at Kirkland-based Directions on Microsoft, said it's no coincidence that Google gave its bad news Thursday.

"They were waiting for Google's first bad earnings report to make this kind of deal. Yahoo has already shown weakness, so they have a better chance of succeeding in a hostile takeover. And it's right at the time when Google is stumbling."

Yahoo's slump helps, too. Making an offer when the company was trading around its 52-week low, which Yahoo was yesterday, is just good shopping. It's like waiting to buy those shoes you want until the Nordstrom's Half-Yearly Sale.

Also of note, Yahoo Chairman Terry Semel, who was most certainly in on the decision to rebuff Microsoft's earlier overtures, left the company Thursday, which was also the date of a company board meeting. Roy Bostock, a board member since May 2003, was elected to serve as Yahoo's non-executive chairman.