Had a play with the Windows Longhorn preview (4051) this week. There's not really anything special to see yet, but at least it's better than XP, which does my head in. The settings are still buried deep in multi-level options windows, and I'm not sure whether moving all the file actions out of the right-click menu and into the top of the folder is a good use of space, but it looks pretty smart - I could well prefer the slate theme to the stripes of Jaguar.
If it can pick up some of the drag-and-droppiness that OS X and Mozilla use for customisation that would be a good thing, and the new sidebar (the one with the massive clock) would be an ideal home for WinAMP, online contacts, RSS headlines ...
Looking forward to the full release (if anyone's still interested by then).