Joost is an Internet based IPTV delivery platform that started as "The Venice Project" in 2006 (http://en.wikipedia.org/wiki/Joost). It uses something called as "P2PTV" to deliver content among it's users (http://en.wikipedia.org/wiki/P2PTV). I had nominated myself as a public beta user for this product many months ago and got my invitation yesterday. So, here are some of the observations of Joost:

-It works on Vista. Although this is not mentioned in the documentation, it's a really good thing for a product that is planning to go public in 2007.

-I had some issues getting the app to work initially - there was an error message that indicated trouble connecting to the network. However there was no option to set network settings anywhere - like set proxy etc. When I tried using Joost later, it mysteriously started working fine.

-Joost needs a user to login from it's interface to get started. The account setup process is a breeze and one can be done from inside the UI.

- Joost can be used either in a full screen app or in a window. In the full screen app, there are controls on all four sides. The channel/volume controls are at the bottom. All the content here is on-demand and there doesn't seem to be any 'live' service.

-Video quality is quite variable - some channels are really jerky with frame-drops and audio-drops, others were remarkably good. Video startup time is between 3 and 10 seconds. Seeks times are same as the startup times.

-The UI is really cool. Channels are organized by category, and programs are placed under these channels.

-One really fancy feature is the ability to chat with friends from inside the interface. Also, one can chat with people watching the current show.

-Ads are placed inline in video programs. However, I don't think different ads can be placed for the same show when watched at different times/by different people.

-Joost used up ~170MB while running, which is not really that bad.

In summary, I think that Joost has a good potential to act as a secondary TV viewing platform and since it uses P2PTV technology it will not have troubles scaling. As more people adopt Joost, the video and audio quality will incrementally get better.