Ubuntu 10.10 gets, while still in Alpha 3, a quite big change at its interface. The default wallpaper has been updated a little (this isn't that big change), but there were new, much cooler wallpapers added from which to choose. Its theme has also been updated, and even if the older one was changing with every update, it has been removed and newer Ambiance and Radiance themes were added.
Ambiance looks really good, nice finished, not like the older one, which seemed so unfinished. Regarding to the new Radiance, it looks so...white. It isn't currently very pleasant for the eyes (it's 9:30 P.M. right now and it's completely dark outside, maybe because of that), and, most probably, changing the brightness of the monitor to a (much) lower value would make it pleasant (or trying it while there's sunny outside).
Anyway, you will feel with these new themes like you are returning a little bit in the past. They are bringing back some of that orange I liked very much at Ubuntu, but now it is much more vibrant than before. Window buttons, which are still on the left side (and I hope they'll remain there), look quite strange now. They are a little bigger than before, but they are interesting.
I can't take screenshots (I don't know why, Ubuntu simply doesn't want to take them), and that's why I am sending you to my friend from WebUpd8, which has made a few screenshots of everything which is new in Ubuntu 10.10 Beta.
I want to remember you that on September 2nd the Beta version of Ubuntu 10.10 is going to be released, the Release Candidate comes on September 30th (it represents around 95% of the final product), and the Final Release is expected on October 10th.