The Panasonic models that Mark recommends are great camcorders, but if you buy them for this purpose, you will be buying a lot of capabilities (e.g., zoom lenses, video recording hardware and software) that you will not be using.
If you don't mind streaming at 720p resolution, a purpose built streaming camera such as the $199 Logitech Broadcaster Wi-Fi Webcam
could be a more efficient and less expensive solution.
This camera is tripod or wall mountable.
You can broadcast from the Logitech directly to UStream without a computer - or you can manage the UStream Broadcaster app through a Mac, iPad or iPhone, as shown here
Hope this is helpful, and good luck with your project,
BillHybrid Camera Revolution