I recently installed CHDK on my Canon A590IS, which allows me to take time lapse photos.
CHDK is a piece of software that provides additional functionality to Canon digital cameras. I have explained it to others as "jailbreaking" my camera, as some have done with their iPhones.
It is admittedly a little complicated to install CHDK onto the camera. The hard part is that you first have to use a hex editor to change the boot sector of the SD card to make it bootable. Once that is done you just copy the CHDK software over to the card, switch it to the locked position, put the card in the camera, and go.
One other caveat is that CHDK works best with FAT16 formatted media, which puts a 2GB limit on the amount of memory that is able to be used. For this reason I bought an extra 2GB card to put the CHDK software on instead of the 4GB card I already had.
Once you have the CHDK loaded there are various scripts that you can run. One script, the Ultra Intervalometer, allows you to specify how many photographs to take at what interval. This is the script I used.
The video you see above is from a set of pictures that were taken from 11:38 p.m. to 12:06 a.m. on New Year's Eve 2008. Make of it what you will. ( ^ _ ^ )
I used the "open image sequence" option in QuickTime Pro to make the video, then uploaded it to my Flickr account (which plays on iPhones).
