Paul Graham recently did an essay on what it takes to create an environment like Silicon Valley (Boulder and Portland were ID'd as top candidates).
Some additional data is coming out, in particular, Tim O'Reilly's blog (click on the title of this entry to go directly to his post).
What's interesting is the above chart.
Apparently, we're number 5 for startup oriented hires in the US. Not bad for a region that's smaller (by millions) than the 4 above it.
So, if you're interested in starting a company, and you don't want to deal with Silicon Valley, it doesn't get much better than Boulder.