Ubuntu uses DEB files but can be persuaded to use RPM quite easily, I'm keeping my fingers crossed for Poser-Linux as it's one of the few programs that's keeping me using Windows.

I'm not in the slightest surprised to see Ubuntu named on the list of supported distros as it's the best I've used so far, runs so much better than Windows & it's free ;)

Windows 7 64Bit
Poser Pro 2010 SR1