With applications such as extrawebcam, extrawebcam.com - turn your Canon digital camera into webcam for video conferencing and more
, it's possible to stream live video from a Canon Powershot to a PC.
Currently there are two limitations that I believe the CHDK could overcome,
1. Increase the resolution from 320x240 up to 640x480, (almost all new Powershots support this mode).
2. Reduce the Jpeg compression level. It's very high at the moment - you can see Jpeg ringing artifacts around high contrast areas.
USB2 can handle 480mbps, (which is roughly 60 MB/sec), so in theory we could send uncompressed video over USB2 and record this stream to an AVI file on a laptop.