Google CEO Eric Schmidt rarely tweets on Twitter -- he has posted 15 messages since Dec. 7 2009 -- but one he posted Feb. 6 struck like a lightning bolt.

The search engine will apparently air an ad during the third quarter of today's NFL Superbowl, which can cost $3 million for just 3 minutes of air time. See Schmidt's tweet:

Google has to do something with that $25 billion of cash in the bank. Why not call attention to itself during the biggest advertising blitz of the year in the U.S.? For those who care, the Indianapolis Colts and the New Orleans Saints will play in the contest.

People of course are speculating: will it be an ad for the Google Nexus One? This would surprise, as, unlike the massive ad campaign for the Motorola Droid by Verizon Wireless, this smartphone has been relegated to word-of-mouth and sales only through the Google Webstore.

John Battelle thinks it could be an ad for search an this ad in particular:

But does the leading search engine in the world really need to tell people about itself? I think 70 percent of the world is well acquainted with Google. Unless of course, Google wants to bash Bing, which could be fun:

For more Google/Superbowl action, see the YouTube AdBlitz channel, where users can go to pick this year's best Superbowl commercial. The winning ad will appear on YouTube's homepage.

You don't have to pick Google's ad. How can anyone compete with the lecherous allure of those GoDaddy.com girls, or the various and sundry commercials of people doing stupid stuff for the sake of beet? But Google wouldn't mind.