Why does my iPod display "Artist Unknown" after I entered in the artists in iTunes?
I faced the same issue after upgrading my iPod touch to iOS 5.1.1. I ended up restoring it to factory settings, and setting to auto-sync with iTunes (I ordinarily prefer to sync it manually!). I also had to change not only all "artist" names but also "album artist" names, as the new software appears to list the music according to album artists.