Just got my new HDTV DVR installed. This is the second attempt by Comcast; the first attempt on Monday this week failed when we found that the cable box would reboot itself every time I went to a menu. This time (Saturday) the installer was one and half hours late, but was very knowledgeable and this time the device worked. It's a dual tuner DVR with a 120 gigabyte hard drive; evidently this means up to 15 hours of HDTV recording.
It's cool; you can record one channel while watching another, and you can pause and rewind live TV. Besides the outputs I'm using (audio over fiber, component video) it also has fireware, usb and ethernet connectors. It'll be interesting to see if these become useful.
Apple's developer software comes with a simple firewire recorder; I understand I could record HDTV streams to my Mac but I won't be able to play them back from there. Not much point to that.