It depends on your camera and computer.
IF you are using a Sony HD camera that uses the AVCHD format, like the HDR-UX5 or UX7, you must have an intel Mac and the newest iMovie for it to work with your computer. The mini-DVD will NOT work in a slot load mac, but you can leave the disk in the camera and the computer can load your footage through the USB 2.0 connection. You may have to "finalize" the disk before iMovie will see it.
Generally, a camera that uses the AVCHD format will only work with an intel Mac. The AVCHD format is also supported in Final Cut Express 4.0, as well as the new iMovie.
brian