It's always worth looking at beta's of upcoming OS releases to see where they are heading...you never know there may be one or two good ideas that should be in Linux....But looking at these shots of Vista I am wondering if MS have sacked half their UI team (if they haven't they should do)
http://www.extremetech.com/article2/0,1697,1931914,00.asp
Check out the media player shot non standard widgets, confusing boundaries between content tree and content files, media buttons that force you to mouse down to the bottom middle of the screen....madness or unfamiliarity clouding my opinion ?
We stuck IE7 preview on a spare XP machine at work, same UI issues, looks pretty but is totally unusable for power users...The only good thing I would like to see implemented in firefox is the tab preview button that gives a screen of thumbnails of all current tabs.