Yeah, most of them are full time postgresql developers working for various companies. Bruce Momjian was working for SRA, a consulting company big in Japan, Jan Wieck I think works for Afilias, the folks who run the technical side of the .org and .info domains (on postgresql, of course.)
Tom and about three other people work on Postgresql for RedHat. They're all nice folks, I've met a few in person, and they're just joe average guys. Except when it comes to coding. 🙂