I have tried bridged networking in CentOS and Ubuntu and ROCKS/CentOS on both Snow and Lion. It seems bridged network is totally broken since I upgraded from 3.x to 4.x. I can ping the host IP if I set the IP statically but not the DNS or gateway. It seems if I switch to NAT everything works. This does not seem to affect Windows7.
Do you use wireless router? Seems bridged to wireless failed on lion, but works on 10.6. But bridged to wired works in both cases.
Wired or wireless, Snow or Lion.. makes no difference, no bridged network on 2 different Macs. Back and forth with support so far no progress.