"Over the past few months, I have been pleased to see a renewed focus on AOL at Time Warner, and the emergence of so many strategic alternatives," said America Online co-founder Steve Case (pictured) as he yesterday resigned from the board of Time Warner. He remains one of Time Warner's biggest individual shareholders.

The timing of Case's resignation is considered ironic by many, since it is precisely now that AOL has emerged from the shadows to find itself what CEO Jonathan Miller called recently the "largest swing voter" in the battle between Microsoft and Google (10% of whose revenues come from an advertising partnership with AOL) to dominate online life.

When interviewed onstage at Web 2.0 recently, Miller said that AOL was "extremely undervalued" since there are still 20 milion AOL subscribers and 60.6M US visitors to its site according to tracker Nielsen/NetRatings. (That makes it fourth. Yahoo! is in no. 1 position, with MSN and Google in second and third place.)

The price for a stake in AOL is rumored to be likely to start at as much as $10BN. The question is, though, will that number go up in a bidding war between the two suitors, Microsoft and Google? And, if so, how high?