So I posted a couple days back about my own troubles with the new 10.6.7 update and I've only found one solution to get iTunes back up & running with no freezes...
Holding down the OPTION key when mopening iTunes will prompt a window that allows you to choose a library or create a new one... I opted for creating a brand new library and then proceeded to add all my songs back (188,000 tracks or so), which was obviously quite time-consuming, but at least I can listen to my music again... Granted, you will lose all your DATE ADDED chronologies and I had to recreate all my SMART PLAYLISTS, but it's the only way I can get iTunes to open and close without freezing up on me in 10.6.7...
I am also going to refrain from syncing my iPhone with this new library until I'm certain APPLE has fixed this glitch... After all, most of the smaller-sized apps can be updated via the APP STORE application itself, yet I won't be able to change the music in the iTunes library on my iPhone until this problem is rectified... I'm currently 2 days into this new library and I've quit iTunes and opened it a couple times, with no freezing nightmares thus far...
I know it's not the most ideal way of getting iTunes to work again, but it's better than silence and sadness...