SHIFT-ENTER closes or opens "blips" which are the things waves are made of.

Double-click a blip to reply/edit that blip.

You can edit someone else's blip as they are editing it. There was some highlighting indicating the other editor at one point but it went away. There doesn't seem a way to identify who typed what if you are in the same blip.

Easy to get lost in a Wave if you are replying to previous blips or editing old ones. Is there a way to manage or sort? Ah ha. Playback mode goes through the wave in chronological order and indicates edits with yellow highlights. 

I'm using Firefox 3.0x. Friend using Safari. Compatibility seems fine.

When you mute a wave you can see it by choosing All from navigation pane. To "unmute," select wave and click the inbox tab.

Finding waves with a particular contact: The search box for the inbox area is not useful unless you know the wave email address. It won't give you a hit off the name (unless I'm missing the query term for it). So you would have to look for "pfhyper" for me and not "Peter". You can search on "Peter" from the contact search and the pop-up will reveal recent waves. (Checking Wave help and they mention you can't actually search on names yet.)

The Google Wave overview video is telling me I can link waves and publish them to my blog. Do you have to use blogger for that? Ah, you need a gadget or robot or something. Wavety.com has a list of robots and gadgets.