Wirecast from Telestream has been around for quite a while, and I have experimented with previous versions, but never had the need for the true capabilities of this software.
In short, this software allows you to manage a webcast like a live tv production with multiple cameras, playback of videos, graphics and more. Wirecast 4 has components to generate a live stream in a variety of formats like Flash, Quicktime, and Youtube. It’s akin to the Newtek Tricaster, but in software.
You can basically throw almost anything into this software, and present it as part of your live show. Using the free “Desktop Presenter” you can even include content from other computers like quicktime movies, web pages, or presentations.
Version 4.2.4 adds a major feature for the Mac version call Virtual Camera Output. This piece allows software like LiveStream or Skype to “see” the Wirecast output without adding more hardware.
The complexity in which one can produce a show is only limited to what one can dream up and interface to with external boxes.
There is a free trial available, that watermarks it’s output, but almost fully functional. Check it out.