Gatineau,
d6d24r94's comment actually worked for me-- I also found another website displaying pretty much the same idea-- it wasn't exactly as straightforward as "step one, step two, step three..." because I ended up doing pretty much the same steps in various orders before it finally took hold.
For that technique to work, you've got to do it individually, as in ONLY sync the apps, then ONLY sync the movies, then ONLY sync the music, etc...
I think it has to do with the iphoto and other apps that need to have their databases updated to the "new" database style for IOS 5-- I wasn't experiencing problems with iPhoto so I didn't consider it as a source of the problem, but I derived a drastic solution that actually did work from a website describing how to delete the iphoto index so that it will rebuild itself.
the solution that really worked for me was to (I use OS X, not sure what to for windows)
1. Quit iTunes
2. Delete the itunes library files. Not the actual data, but all the helper files in ~/music/itunes such as "iTunes Music Library.xml" and "iTunes Library Extras.itdb"--- I trashed them all but didn't empty trash just in case. Again- I didn't erase any actual MEDIA or APPS, I just erased those little xml and database files.
3. Open iTunes again and tell it to look in my home directory for media.
This solution is drastic-- it forces iTunes to think it has nothing whatsoever. So, for that particular iPad and iMac, I had to rebuild the entire music library from scratch-- luckily on that computer it was all of an 8GB music collection. The music files were still there, so it was just a matter of iTunes finding them again and then processing all the album artwork and genius...
next, I had to get my apps and books and other purchases from the store back. Just use the iTunes Store side tab within iTunes, sign in to your account if you're not already, and click the "Purchases" link, which will bring up all your purchases and allow you to download them again.
Like I said, this is DRASTIC. I don't know if it's the RIGHT way or if there is a better, easier, way-- but these steps worked for me. the iPad now syncs just fine, seems to have no issues whatsoever, and even seems to be doing the auto-sync via WiFi just fine...