The new Mac Mini line looks to be in the same ball park as a refurb Mac Pro (6 core i7, 32GB, 1TB SSD, $2499), but it supports the latest Mac OS X and has Thunderbolt ports.
With some adaptoring, I think it'll even be able to drive my two Apple 30" monitors. I write code, so video resolution/performance has absolutely no bearing on my needs at all.
The new Mac Pro (next year?) needs to be a significant step up to have me looking away from a high end Mac Mini.