I think I get Google Wave, at this stage. I've seen how it can be a useful tool at work, among a small number of people working on a specific project.
What I want to know, given that it's web-based, is: does a wave have a canonical URL?
If so, are there querystring parameters that I might want to set to set the state of the wave? If I send someone a link to a wave in an email, what do I need to know about them to be sure that they will actually be able to see that wave?