I don't think this is exactly what you are looking for, but it is a variation on the time lapse photo. I wanted to take a long duration exposure of star trails, but my Canon S3-IS doesn't have a "bulb" function. Instead, I used the "intervalometer" function to take 30 photos, 1 minute apart, each with a 15 second exposure. Definitely not as good as a true 30 minute exposure, but not bad considering the limitations of the camera. The 30 photos were combined in Paint Shop Pro. The trees are a little blurry due to wind throughout the 30 photos.

Matt