Khakis, with brown shoes. Not tennis shoes, although trendy sneakers (but not athletic shoes) would be considered.
The most insulting part: the Microsoft keynote speakers - MS employees - were in jeans and track suits. They were trying to look approachable. Hilarious because you couldn't approach them and ask a question during keynotes.
I'm a Microsoft employee who has spoken at one TechEd and staffed a booth at another. Rest assured, the style cops were all over us to conform to the dress code. I can believe that there's a different standard for keynote speakers, who are usually notable or "important" in some way.
The most insulting part: the Microsoft keynote speakers - MS employees - were in jeans and track suits. They were trying to look approachable. Hilarious because you couldn't approach them and ask a question during keynotes.