TVersity: freeware, simple to install, can be a bit fiddly to configure (firewall ports, etc.), does not display album art but tracks are in correct order, and PS3 has trouble picking up the server presence. Overall, not too bad but could be better.
Nero 8: licensed, simple but long to install, Nero Scout is fairly heinous but a necessary evil, crashes when trying to import iTunes library, displays album art on tracks but tracks are ordered alphabetically by track name, PS3 picks up server presence easily. Overall, I think this had potential but turned out to be a load of pants.
TwonkyMedia: licensed but cheap, simple and quick to install, imports iTunes library, displays album art on tracks and tracks are in correct order, does do something funny with metatags (e.g. "The Band" becomes "Band, The"), and PS3 easily picks up server presence. Overall, I think I could be onto a winner.