It's not too late to RSVP to the online advertising arms race, Microsoft (NASDAQ:MSFT). This morning's New York Post indicates that the world's largest software company may be making a play for interactive marketing specialist 24/7 Real Media (NASDAQ:TFSM).

Shares of 24/7 Real Media shot up to as high as $13 this morning before pulling back later in the afternoon. The $1 billion price tag pegs the value closer to $20 a share, but the stock isn't gong to approach that level unless a deal is in place.

Naturally, just because a rumor gets put into print doesn't make it happen. Last week, it was advertising giant WPP (NASDAQ:WPPGY) that was supposedly interested in 24/7 Real Media as a way to grow its presence in Web-based marketing.

Yahoo! (NASDAQ:YHOO) announced a $680 million deal to acquire the 80% of Right Media that it didn't already own. This follows Google's (NASDAQ:GOOG) larger $3.1 billion deal to acquire DoubleClick, a company that Microsoft was originally reported to have been going after.

So, hold on to your hats. The trend is real, but it could also be dangerous to investors. Shares of 24/7 Real Media, aQuantive (NASDAQ:AQNT), and ValueClick (NASDAQ:VCLK) have all inched higher in anticipation of buyouts in the interactive marketing industry. More deals are likely to happen, though the value of those left behind may lose a little air once reality sets in.

You don't trade on the rumor, but it sure makes it fun to watch.

Yahoo! is a Motley Fool Stock Advisor newsletter selection. Microsoft is an Inside Value recommendation. aQuantive is a Rule Breakers stock pick. All three newsletters are currently beating the market, and you can find out why with a 30-day trial subscription.

Longtime Fool contributor Rick Munarriz enjoys a good buyout battle, but usually from a safe distance. He does not own shares in any of the companies in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.