Here are two time-lapse videos I made with my Canon Powershot G9 + CHDK:
These were shot mostly at 4000x3000 resolution, and then scaled/edited using VirtualDub and AVIDemux2. The level of quality you can get from this process is pretty amazing, and easily results in much higher quality video than you would typically get from a camcorder.
CHDK itself is quite simple to use and there are lots of scripts available that other people have made. For my purposes, I decided to take a couple of the most popular time-lapse scripts and wrote my own based on their features. You can code the scripts in either BASIC or Lua, both of which are pretty easy to get to grips with.
Canon is up to the Powershot G11 now, but even my older G9 is still very powerful and an absolute joy to use. The main disadvantages are that it’s still firmly placed within the “compact camera” genre, so you do lose some of the flexibility that you’d find on something more like a digital SLR, like having a really nice depth of field (though you can still manage to nicely blur the background on shots by switching to macro mode). Its low light performance is also not AMAZING, but it is definitely no problem to take shots at night with a longer exposure time if you have any kind of tripod (I use a Joby Gorillapod which is simply awesome), and when doing long exposures on the lowest ISO setting, the shots come out crystal clear as you can see in my first video (direct images from the camera, no form of noise reduction was performed).
Another thing is that despite being on its 11th revision, the camera still only shoots video natively at 640x480x30fps (or 1024x768x15fps). The G12 will be arriving soon and will supposedly offer HD video, but I have seen rumours that this will only be possible in black&white mode, which seems rather silly to me.
Either way, they’re great cameras which are extremely well built and feel rock solid, they’re extremely easy to use, and they’re small enough so that you can bring them pretty anywhere with you and take shots whenever the mood strikes you. I carry mine around in my messenger bag pretty much every time I go out, just in case I stumble across something I like.
If you are mainly focused on taking great photographs and doing time-lapse video, then I think a Powershot + CHDK would be an excellent and relatively cheap investment.