User-created read-only waves are in the works. I could (now) write a robot for you that, when invited to a wave, would undo any changes anyone made. :-)

The UI is clunky for it, but I can do multiple waves at once, using multiple windows. I should be able to middle-click on a wave to open it in another window/tab, but that doesn't work. Still, I can go to wave.google.com in multiple windows.

If wave catches on, I expect there will be local UIs, and better UIs.