CYA is a toolkit for sensing people in spaces. It is available as a Beta version and is being developed by LAB at Rockwell Group, IDEO and James George. The basic structure is a server-client model with the CYA server sending OSC, TUIO style OSC, or TCP information to a client which could be in Processing, Flash, PD, Max, etc. (anything that can listen to OSC).
Here’s a simple Processing example (zip file includes the CYA application and the required Processing OSC library) – download
You can find an openFrameworks post that discusses a bit more about it here
You can find the LAB at Rockwell Group site here