I've been experiencing this issue as well, both before and after upgrading to I8, and both before and after upgrading to Bonjour 1.0.5. Typically, iTunes will launch properly after a roboot, but if it's shut down and relaunched the error message re: Bonjour will appear and my AirPort Express won't be found (so I can't stream to my stereo via AirTunes).
In response to Snoop Dogg's post, Bonjour Console Utility accesses the Internet, registers Foobar, gets a reply, and reports that the name is now registered and active. For what it's worth, iTunes still can't find my AirPort Express after running the command.
I'm running TrendMicro 8.0 SP1 for anti-virus and ZoneAlarm 7.0.483.000 with the 5.0.189.0 version of the anti-spyware engine for my firewall. Both may have auto-updated recently, but I can't say one way or the other with certainty.