The Cool Features -- Over the air sync (don't need to dock!), WMA Lossless Support, and a Glass screen instead of the easily scratched plastic ones on the Zune 1.0.
But the nest feature of all is support for Media Center. You can now sync recordings from your Windows Media Center to the Zune and take your favorite shows with you.
That alone is worth the price of admission!
***Updated*** Engadget has posted some specs...