As we all twiddle our thumbs while waiting for the next-generation of Zunes to ship out
has pointed out
a number of user interface changes to tide you over. Notable differences include the volume setting reaching 40 (versus 20 on the existing models), album artwork when browsing by Album looks bigger than on the current firmware and when advancing from one track to another, the album art for the new track slides in from the right in a "wipe" transition. Granted, most of these changes aren't apt to make or break your experience with the new players, but if you're interested in checking out the full list, the read link's got the goods.