[Greg McKaskle]

I believe most USB webcams have an upper limit of 30fps. The difference between them and the kit cameras is that the kit cameras are compressing the image and sending it over 100MBit enet. Since the USB2.0 spec allows more bandwidth, about 480 MBit theoretical, the camera streams are usually not compressed, though the Kinect does compression for the higher resolution modes.

Fortunately, kit cameras were selected that do the compression in HW, so they don't introduce much lag.

For industry, where camera rates and resolutions are often much higher, USB is becoming popular along with other standards such as GigE (gigabit ethernet), 1394 (FireWire), and Camera Link.

Greg McKaskle