Apparently the "CSI" interface is not really standardized like a USB interface or RS-232 serial interface. There is no standard connector, no standard pinout, and no standard driver, so nothing would be plug-and-play. You'd need an adaptor board to properly connect any "CSI" camera to the R-Pi, but even more significant is that you'd need to write the driver, which has to run on the GPU and would be a lot of work even if the GPU documentation was available- which it isn't.
From what we've been told, we will have to wait until a specific camera device is chosen, an interface board laid out, and a suitable driver for it written to run on the GPU.
Note: did you know, you can get a USB Webcam for less than $5 (although I don't know if it could work on the Pi):
http://www.ebay.com/itm/Mini-USB-Webcam ... 0911025206
For $15, this one claims to work with Linux, as long as you have a USB Video Class driver:
http://www.ebay.com/itm/USB-WEBCAM-Came ... 0429028863