Sounds cool, but what would you use it for? Just running a playstation emulator and playing games seems a bit circuitous. Being able to play around with controller input, a shell, and basic graphical applications would be a lot of fun though.
From what I understand, Gentoo supports the Power architecture that PS3 is built off of, but my concern would be that drivers for the co-processor and other hardware/io aren't supported for the (mainline) linux kernel. You can hack your way around that, but it'd be out of my comfort zone at least.
If you're asking whether you could run binaries used by the normal PS3 operating system within a Gentoo system, then I'd assume the answer is no, because they could have entirely different object file formats, linking, etc.