I work in an office with WP Engine and Other Inbox (recently acquired by Return Path.) There are plenty of startups here; the Capital Factory folks probably know many of them.

I moved here from the Bay Area (with a 2-year stay in San Diego in the middle) and I'm really happy with the quality of life and the tech community here in Austin. I can buy a house and live comfortably here, and the taxes are far cheaper--important when you really start earning money!