In reply to The Lemming:
I would shoot RAW for sure as it gives you heaps more options in post (although i mean more options to tweak dynamic range, just get WB right in camera!) however think about processing before shooting RAW, as 10gb odd RAW sequences makes even high end servers chug so depends on what your editing on. If you get it all right in cam then jpeg is fine, and if you dont get it right in cam, you really want to tweak 240 images?!?!
That extra size in terms of image vs hd video is useful IMHO to allow u to pan and crop in post afterwards though and create a few interesting effects etc
a lot of DSLRS allow you to shoot both raw and jpeg, so you if you use something like adobe after effects you can use the jpeg sequence as a proxy for your RAW, edit tweak and then render the raw (which takes ages!!)
re: intervalometer is essential if you DSLR cannot do it in Cam (most canons can take advantage of the magic lantern sd card hack if you need it and worth a play)
I would shoot all manual but take other posters point about aperture priority mode, but still pick your time and light well and shoot all manual if u can to avoid flicker etc! LRT timelapse is a cool bit of software that allows you to blend frames and deflicker if it gets too bad
Critically though use an ND filter if you can during daylight....those gorgeous time-lapse you see are usually always filtered and dragging the shutter with longer exposures for the aperture (longer u can expose for whilst not blowing things out, is my personal preference and gives motion blur rather than stop start animation )
use a tripod and remember at 24fps you need at least 240 frames to make around 10secs of footage at 30fps of course higher (seriously this is what most ppl under estimate esp at night as takes forever and you can be out for hours so frame it well, dont rush the set up and have fun!!) heaps of good info here
http://timescapes.org/
Oh and shameless plug whilst we are on the topic, I shot this in peru a while ago on a little trip heaps of time lapses in the evenings, and was fortunate to be out there when we had that super moon a while ago! enjoy!