"There are opportunities for us to accelerate our execution in this area," he said. "We've done a lot of work to make sure we have a team that will be able to accelerate it."

Microsoft, which recently said that a Windows Mobile software update will come later this year, has been criticized for failing to improve its platform to better compete with the iPhone and other new touch screen phones.

Ballmer responded to a wide range of questions during the CIO Summit Wednesday, an annual event hosted by Microsoft for government and education sector IT workers. His comments about Windows Mobile were in response to questions from an IT administrator from NASA who challenged Ballmer to offer advice on how to deal with workers who bring consumer devices like the Android G1 and the iPhone into the work place.

Those devices don't meet the security requirements that some organizations have while Windows Mobile devices do, but users don't want Windows Mobile phones, the attendee said.

One of the challenges Microsoft faces is that Windows Mobile supports various kinds of form factors, Ballmer said. "In general, I'll make the argument that having diversity of form factor serves the broadest set of the population," he said. "The question is how simple can we make it to write an application that runs in multiple modalities."