The Microsoft Corp. (NASDAQ: MSFT) -- Yahoo Inc. (NASDAQ: YHOO) merger dance is not quite over yet.

In an open letter to his fellow long-suffering Yahoo shareholders, billionaire Carl Icahn disclosed that he has spoken "frequently" with Microsoft CEO Steve Ballmer; "frequently" over the past week about Yahoo. Ballmer indicated to Icahn that the world's largest software company would still be interested in doing a deal ... with one catch.

"Steve made it abundantly clear that, due to his experiences with Yahoo! during the past several months, he cannot negotiate any transaction with the current board," Icahn said. "If a new board were elected, he would be interested in discussing a major transaction with Yahoo!, such as either a transaction to purchase the "Search" function with large financial guarantees or, in the alternative, purchasing the whole company. He stated that Microsoft would be willing to enter into discussion immediately if the new board that has been nominated were elected."

In a separate press release, Microsoft underscored Icahn's statement, adding that despite speaking with Yahoo!'s board since last year, the company decided that it cannot reach an agreement with the current board. Can you say trial balloon?

Though time is on Microsoft Corp. (NASDAQ: MSFT)'s side in its $44.6 billion unsolicited takeover battle for Yahoo! Inc., (NASDAQ: YHOO), that doesn't necessarily mean it will win the war.

The world's largest software company late Monday said -- predictably -- it was disappointed that Yahoo "has not embraced our full and fair proposal to combine our companies" and that it was "confident that moving forward promptly to consummate a transaction is in the best interests of all parties.''

You didn't have to be psychic to see that coming.

But Yahoo co-founder and chief executive Jerry Yang isn't stupid. Microsoft, like News Corp (NYSE: NWS) in its pursuit of Dow Jones & Co. is an uneconomic buyer of Yahoo. Steve Ballmer wants to make sure that Yahoo doesn't fall into the hands of the either Google Inc. (NASDAQ: GOOG) or a media conglomerate such as Time Warner Inc. (NYSE: TWX), parent company of AOL. He has already pledged to pay a 62% premium for a company that many on Wall Street believe has seen its best days.