At the Web 2.0 Summit in San Francisco, Ballmer trotted out a common attack on Android, suggesting that the mobile operating system is too complicated for ordinary users. "You don't need to be a computer scientist to use a Windows phone and you do to use an Android phone," he said, . "...It is hard for me to be excited about the Android phones."

Ballmer that "the cheapest phones will be Android, and we are going to have to look at bringing the cost of our handsets down."

But Ballmer wasn't as quick to dismiss Apple's iPhone. He commended Siri, the virtual assistant featured in the iPhone 4S, and said that Apple is "a good competitor, but a different one." He then touted Windows Phones' ability to display information on live tiles so users don't have to scroll through a sea of icons.

"A Windows phone gets things done," Ballmer said.

Mincing words on the iPhone was probably a wise move for Ballmer, who in 2007 famously there was "no chance that the iPhone is going to get any significant market share." Today, the iPhone is the in the world, and the iPhone 4S sold 4 million units in its opening weekend.