I've often thought that my next console will be a HTPC box. Advantages: OS of choice, emulators, infinite other homebrew, replaceable/upgradeable parts, complete user customization, freedom from $ony and Micro$oft.
Disadvantages: cost (a bit more than what i paid for my 80gig BC PS3), the inconvenience of manually tweaking games for best performance, loss of a handful of "exclusive" games. Still ... I've nearly convinced myself, especially with how $ony has behaved these last few months.