Ya matt this is a really good resource. www.prophotoirvine.com also has some cheap rental rates for comparison.
I second Pro Photo Connection in Irvine. They don't have the largest selection, but pricing is good, and Gunther is a hoot to chat with. Ask him for stories ... tell him Shauna the Lebanese sent you. :)I met Vinny at Borrow Lenses at WPPI, and he was fun. That's about all I know. I'll be renting from them the first time in a month or so. I'll keep ya'll posted on the experience.