I have the same problem. Hangs at about 85% finished.
I wonder if it is because I update some of the apps on the ipad and some on the Mac.
Perhaps it should be updated in only 1 place. I usually grab most of them directly on the iPad.
Then after it is synced I could update the apps that are on the Mac.
Has anyone noticed this happening?
Here is my workaround:
cancel sync on device
unplug device by removing the cable
iTunes may still be spinning
quit or force quit iTunes
reset device by holding home and on button until you see the apple logo
If it says backup did not work, ignore that
backup works with this sync
At last - a succesfull backup! Had to delete my Sunday Times app, and my T3 magazine app (thus losing a years worth of magazines) but success none the less.
Many threads have said similar things in that magazine app files contain lots of data - perhaps some became corrupt?
Syncing s now fast and painless, and best of all 'Backup' is turned back on.