I today got a hint about a very capable video capture box. LiveWedge from Cerevo can take 4 HDMI inputs for switching including chroma key and produce a video stream to Ustream and other services. You control all aspects including audio mixing via a webinterface from your tablet.
All under US 1000.
It was introduced at CES this year and as I understand they are initially targeting US and Japan markets. Would be great to get hands-on…