I have blogged about Joost a few times before, but the system now works even better than before: better looking video, very few pauses in video stream, and more interesting material.
One thing about Joost: the commercials are short and unobtrusive. I actually wish that they would include more commercials to ensure that as a company they stay in business. Good stuff!
I think that ABC also does Internet video very well (on my MacBook, they is a one time Java plugin installation). However, I like the more "Indy" style material on Joost. I also prefer Joost's technical approach of using a "rich client": not everything has to happen in a web browser. That said, I would hope that all major networks follow ABC's lead.