OUAnthony is correct. (iCam and the iCamSource support MJPEG and JPEG streams from network IP cameras.)
There are some h.264 cameras that still support either MJPEG streams or at least still JPEG image URLs.
If the camera does not support MJPEG you can still use it with the iCamSource and iCam if you can get a still image JPEG from a URL. (You just need to use the JPEG radio button in the iCamSource instead of the MJPEG one.)
Since every camera is different, I would suggest contacting the manufacturer to see if the camera provides either an MJPEG or JPEG URL. (This forum post on their site does look promising, though:
http://forum.ubnt.com/showthread.php?p=239038 ... Perhaps they support a snapshot.jpg URL.)
The issues with h.264 are primarily licensing concerns and CPU usage. h.264 is used because it gives you a higher-quality stream with less bandwidth. The problem is that you need much more computing power to decode and process a stream into something viewable. (Everything has trade-offs.)
iPhones and iPads can decode h.264 streams, but only one stream at a time. (You can't create multiple h.264 video playing controls simultaneously ... The hardware just doesn't support it.)
iCam and iSpy Cameras use MJPEG (which is just a series of JPEG images) to display their video streams. If we used h.264 you wouldn't be able to view multiple thumbnail streams at once, so it's just not practical for our uses.