It is simple, just double-click on the content area where you are reading the wave. It will show two options - reply and edit. Select "edit" and you are done, it will open-up the editor. This is much faster than selecting “Edit this wave” from the menu at top-right.
2. Read-only wave
When you make a wave public, by adding email@example.com, you now get an option whether you want to give read only access to the new user or full editable access.
Read-only participants can only view the wave and look at the history. But they can neither add anybody to the wave, nor can they make any modification to the wave.
3. Add Google Groups to wave
You can add a Google Group to a wave, set permissions and then view and edit waves with that group. This is a very useful feature for a person like me who uses wave for group collaboration half the times. In one of my astrology forum, I used Google Wiki for writing an ebook with my forum members and Google Wave is even better.
4. Revert to older version
Wave version control got better after introducing option for reverting to older version. You now get "Restore" option during playback (while checking the history)
Love you Google and Google Wave. Looking forward to the invitation for Google Wave on my Google Apps.
Important Note for New User:
(As on 22nd April 2010, now you can remove a user from the wave)
Google Wave for Dummies