The AllThingsD blog reported that under the terms of the proposed deal, the two companies will share related search-advertising revenue, as opposed to having Microsoft simply offer Yahoo a hefty up-front payment in order to grant it access to Yahoo's search engine.

In addition, the online edition of The Wall Street Journal reported that the deal will likely involve Yahoo agreeing to use Microsoft's search engine on its sites, while Microsoft would allow Yahoo to handle search advertising sales for both Yahoo sites and some Microsoft sites.

A representative from Microsoft did not immediately respond to a request for comment. A Yahoo spokeswoman declined to comment.

Both Microsoft and Yahoo have long been struggling to gain ground on U.S. online search-market leader Google Inc. 

Microsoft mounted an unsolicited takeover bid for Yahoo last year with the intention of teaming up against Google, though Yahoo proved reluctant to entertain the offer and it was ultimately dropped.

However, Microsoft last year also began publicly floating the idea that it could simply partner with Yahoo on search, as opposed to pursuing a full merger.

Yahoo Chief Executive Carol Bartz, who was appointed in January after her predecessor Jerry Yang was forced to step aside, has joked in public that Microsoft would have to offer a "boatload" of money to make such a deal feasible.

However, more recently Bartz has publicly praised Microsoft's revamped search engine, called Bing, which was unveiled in late May.

Some Yahoo investors and Wall Street analysts covering Yahoo have advocated a search partnership with Microsoft, arguing that handing over control of its search business could save Yahoo money and enable it to focus on the sale of graphical, display advertising -- a market that Google is increasingly interested in.

Bartz has countered such arguments by saying that the user preferences and data culled through Yahoo's search service are invaluable for the company's display advertising.

Early indications are that Bing has helped Microsoft draw in an increased number of search users, though Microsoft remains stuck in third place in terms of U.S. market share.

According to data from ComScore Inc., Microsoft held 8% of the U.S. search market in June, while Yahoo held 20% and Google had 65%.

Last February, Microsoft offered to buy all of Yahoo for $40+ billion.  Last summer, Microsoft offered to buy Yahoo's search business for $1 billion. 

A couple of months ago, Yahoo CEO Carol Bartz said it would take "a boatload" of money to get her to sell Yahoo's search business.  Two weeks ago, a report suggested that the finally-impending deal price tag would be "several billion."

And now the deal is done, says Kara Swisher.  And we know the actual price:

Zero.