Yahoo and Microsoft continued their “Will they? Won’t They?” dance this week regarding online advertising partnerships. Executives at each company spoke up on the topic today, with Microsoft making it clear that it is open to a deal and Yahoo remaining cryptic on the topic.

Microsoft president and CEO Steve Ballmer spoke first this week about resurrecting a Yahoo deal from the ashes of last year’s aborted acquisition attempt.

"We remain open to a partnership with Yahoo," Ballmer said in a speech at the Cannes Lion 2009 advertising festival.

Meanwhile, at today’s Yahoo shareholder’s meeting, CEO Carol Bartz kept mostly mum on the topic.

"If we ever have a deal with Microsoft it will be announced publicly and until we do, we have nothing to say," Bartz told shareholders, according to a Dow Jones Newswire report.

Ballmer didn’t go into detail about Microsoft’s most recent dealings with Yahoo—responding with an enigmatic “Who knows?” to questioning of whether the two companies would shake hands in the next year.

One might wonder why Microsoft would continue to court Yahoo following the Internet giant’s hot-then-cold routine over the last year. Advertising analysts with comScore report that the company does hold a pitiful 8 percent of the market compared to Yahoo’s moderate 20 percent and  Google’s commanding 68 percent. But even while Microsoft is still struggling to catch up with Yahoo, it does have a marked advantage in its deep pool of resources and in the latest launch of the Bing search engine.

Released last month as what Microsoft has dubbed a “decision engine,” Bing has strong commercial components that look to integrate into the company’s advertising strategy. The question now is how Yahoo would fit into that new model.