Hal you are now 4th in line for an invite although I dont have any as of now...
The broadcast quality isn't bad at all. It lags a bit at first but once it gets a good buffer it is fine. I would say it is comparable to regular TV, plus I think it goes up in quality as it buffers or at least it seems that way.
Again it is def a beta and has some kinks that need to be worked out but it def. has potential.
I am especially curious about the widgets in the "my joost" section apparently you and other content providers will be able to make your own. Right now it does have chat as in you can chat with people watching the same channel as you, which could be way cool for debate type stuff and educational purposes. Since you can pause it getting into a discussion about something would not cause you to miss anything...
Some links of interest at the joost site:
Screen shots -
http://www.joost.com/screenshots/
Current channels list -
http://www.joost.com/whatson/channels.html
-edit
It is also available for Mac OSX as well as XP... I bet there will be a linux version at some point too
I can maybe save the release notes so you can view them but as of now you have to have an account and be logged in to see them...