the solution which works for me for both of my ipad and ipad 2 is. looking at the size of "Others", see which portion of "books" or "musics" or "itune U", etc matches best. it could be a sum of them.
remove the "tick" from sync in itune for the tab which matches the size. for example the Others appear to be the size of all your books, then remove the tick from sync for books.
then sync;
after it finishes, you should see the "Others" has gone down. the size should be about 500M. if not keep doing the above procedure until the size is down to about 500MB.
then you can click back the sync "checkbox" to sync back to ipad. this time you won't get a big "Others".
takes a while unfortunately.
i am this wouldn't happen if you install iOS5 without restoring first. install it as fresh device. then sync the wanted musics, books, etc.
i have seen this problem on development version of iOS 5.