I recently had a play with using the intervalometer function to do night-time time-lapse with my powershot A800. To avoid problems with batteries constantly running out I needed a mains power lead; with canon wanting £50 for their one I decided to build my own. Is is no masterpiece, but I was able to build it with things I had lying around and it does the job with no problems.
I wrote up the whole process on
my blog.
Thanks,
Mike