Everytime I tried to sync iPhone 4 using latest iTunes and iOS 5.0 the sync would hang up at step 7 of 7 (copying files) I just ejected the iPhone and hoped for the best. Everything seemed to be there.
Read that the OTHER cat. was growing with each "uncompleted" sync. This is happening to me also.
Got the iOS 5.0.1 and it was still happening however today, it seemed to work.
I still don't know what the OTHER category is on my status bar.