I've successfully used the QAM tuner on my Mitsubishi to get the HD locals from Comcast here in Arlington, VA. (It was a pain to find the channel numbers, but after some trial and error I figured it out.) This doesn't get you anywhere, right now, on the recording front though, since it doesn't work with DVHS recorders for QAM; the Mitsubishi sends the entire channel stream to the DVHS (including all subchannels), but that stream contains too much data for the DVHS to handle (28 Mbps versus 19 for a standard ATSC stream, including subchannels, if I recall correctly). I should also add the proviso that this doesn't work everywhere, since a number of people have reported their local cable system scrambles even the local channels; the Mitsubishi tuner can only handle unencrypted QAM.
Soon, though, the integrated Mitsubishi will be a good solution when combined with the upcoming RCA AV hard drive (just $449); there's no reason this shouldn't work with QAM since it's just a harddrive. And of course the forthcoming coming FireBus software will allow you to hook up the integrated Mitsubishi TV to your computer and use that as basic hard drive recorder.
I wish one of these products would come out soon, though, since the fall season is just about to get started!