Looking forward to the single-camera life for family pics and vids, and very interested in DSLR for video. I have Pentax lenses from film SLRs (1990's models), and was looking at the Pentax DSLR that now does HD video (The K7, says it does 720p at 30fps with on-board mic and miniplug mono input) since I have lenses just sitting.
I'm used to miniDV world, and my current video gear is FinalCutStudio-2, and a Tascam 2-ch porta-Dat recorder (DA-P1, xlr and line in/out).
Could the K7 fit in that workflow okay?
Would some of the other models (some friends like the Nikons for their filmmaking work) fit in, including using Pentax lenses?
I haven't heard very much buzz about the K7's video mode, though it certainly appears to be a nice camera. As for the Nikons, they're great for stills but the video isn't quite as impressive.
Canon seems to be where the action is with dual use video/still cams. You can use Pentax lenses on Canon EOS cameras with a cheap adapter, though they'll be manual focus/aperture only. If you have some really great Pentax glass, you could use it that way without sticking to Pentax bodies. I'm doing that with some Olympus lenses on my new Canon T2i. The video is quite impressive, and manual focus is preferred for motion use anyway.
Your TASCAM may come in handy; audio recording is currently lousy on most DSLRs so you may want to use it for audio and sync it up to your video in post, just like the film guys have always done.