We all know its coming, but according to 9to5Mac sources, Apple are recently began internally seeding the next major release of iTunes, iTunes 11. Work on iTunes 11 reportedly began before the release of iTunes 10.6, and the development of the new version 11 product is said to focus on under-the-hood changes, rather than cosmetic changes - a good sign.
But, Apple does develop different portions of products in separate groups or at separate times, which means the final version we will see, could be different, and thus, could sport a refreshed UI. Apple is working on iTunes 11 for it to support iOS 6-based devices, as well as future Apple devices. Apple usually releases new versions of iTunes to coincide with new OS's and mobile devices.
One of 9to5Mac's sources does note that we could expect another 10.x release, with support for iOS 6, and then iTunes 11 would arrive later on in the year. iTunes 11 is said to include more iCloud integration.