As if an abbreviated bear hug from Microsoft ( MSFT ) weren't enough, Yahoo ( YHOO ) now has a new foe: Carl Icahn. The billionaire corporate raider launched a battle to win control of the board of the embattled Internet pioneer, nominating a slate of 10 dissident directors that includes himself. Icahn outlined his intentions in a May 15 letter to Yahoo Chairman Roy Bostock, faulting Yahoo for how it handled the takeover approach from Microsoft, which on May 3 walked away. "The board of directors of Yahoo has acted irrationally and lost the faith of shareholders and Microsoft," Icahn wrote.