For those that didn’t want to sit through the huge 80-minute video on Google Wave, here are some of the features in short chunks.
As posted at http://www.lifehacker.com.au/2009/06/the-google-wave-highlight-reel/

I’ll warn you up front that streaming video from TubeChop is very slow – good luck.
Original video here.

Inline Replies

As-You-Type Live Updates Over the Internet Between Users

Wave Revision Playback

Private Replies

Embed Waves into Web Pages

Live Collaboration on a Single Wave

Live-Updating Search Results

Contextual Spellcheck