There is a THRIVING community of HD DSLR video creators on Vimeo. Search around a bit on there, the examples are generally breathtaking. I don't know too much about DSLR video capacities (I'm very interested to know how long of a take they can make: I personally often have many long takes and shots so a 1 minute video limit or whatever could be crippling, but I just don't know what the reality is) but I do know that there are some wonderful and GORGEOUS short films made using them. Check this out as an example: http://vimeo.com/7152063

It's funny, I think I'm able to tell pretty darn accurately which videos on Vimeo are DSLR or camcorder now, don't know exactly why. Most of the cameras I see on there though are upwards of $2000 (the higher up EOS models usually, MKII and such) though, so I don't know exactly how the video on a sub $1000 DSLR would compare to a camcorder in the same range (though after looking at the XH-A1 I can assure you the video capabilities would be better on that thing than the Rebel...).

Hope that helps a bit, it should help to SEE the kinds of footage people get with those things. And I'm by no means trying to advertise Vimeo or anything here, it's just a place where I know a relevant community exists.

Most obvious difference (which is usually how one can tell a camcorder from DSLR shot) is depth of field. Because these DSLRs have much larger sensors than tiny toenail-sized consumer (and even some semi-pro) camcorders, you need much longer focal length for same viewing angle, hence much shorter depth of field.

Two most significant issues with the DSLRs, neither major for serious filmmaking:

1. Poor audio. Most don't have external connectors, and if they do, they are cheap 1/8" type (like $500 consumer camcorders);
2. No dynamic focus or exposure adjustment in auto mode (i.e. when you acquire focus and exposure before the shot, it stays locked during the shot);

As I said, neither of the two presents a serious obstacle to a filmmaker. Audio is usually recorded separately and synchronised in post. Focus (and aperture) can be pulled manually, as is usually done on pro cameras anyway.

In addition to these, the remaining issue is the capturing format (MPEG-4 in an ordinary MOV or AVI container, instead of AVCHD), which may present some issues in transcoding and/or editing.

There is an increasing number of people in the independent film community who are very excited by DSLRs, and are convinced they could get more creative shots with them than with a HMC-150 or something similar. While these DSLRs are all single-chip cameras, their sensor size is so much larger than the three-chip HMC-150, for example, that it more than makes up for the difference.

Convergence has been happening for a number of years now, with cameras being able to shoot some video, and camcorders being able to shoot some pictures, but last two years brought this convergence much closer, with 8-megapixel camcorder sensors, and 1080p HD video from still cameras. I have no doubt that the manufacturers (many of whom make both camcorders, as well as still cameras) will play it very, very carefully, not to tilt the balance too much into one or the other category, so we should expect camcorders to continue to gain features that would be of interest to filmmakers and would get them to chose those over DSLRs (features such as over-cranking, for example).

Still, DSLRs have made their way into indie filmmaking and they're likely to remain popular choice.