The 'PS3 Megabox homebrew project' has brought Freevo to the PS3. The description of the software states Freevo allows you to manage your entire digital media collection - music, videos, photos etc. via a remote controlled TV interface and through the built in web interface you can also access your media, view your TV guide and schedule recordings from anywhere in the world. The benefit of freevo above other HTPC solutions is that freevo is 100% DRM free, plays video in 99.99% of formats, and most of all puts you in control of the television. From what we can tell, the description says you don't have to install it and can just run it off from USB.
Instructions
1. Install Petitboot Loader
2. Burn 'this image' to a CD/DVD
3. Start petitboot loader, like other bootloaders on your PS3
4. put in the CD/DVD you just burned and select the icon using the petitboot
5. launch the 2nd icon
6. YEAH, its running!
Via Maxconsoles