actually, both of my computers are running the most up to date version of i-tunes--i always keep up with the updates (my OS-X updater is set to automatically check for updates every day, on both computers).

see my comment to glaucon for what the new i-tunes library did with the first song from reginal spektor's album, as an example of why this is weird.

i think the speakerboxx guest artist songs were separated in my old i-tunes library too; it just looks more pronounced in this i-tunes library because i'm using the album view rather than the basic song-list view. (if you have i-tunes, i'm using the middle option on the view menu, which puts the album artwork to the left of the song list for that album.)