This is a test sequence. I have a small tripod mount for my iPhone 4 (called the Glif), and put the phone on the tripod this morning while doing other things. I used the TimeLapse app, which is a highly configurable app for shooting interval photos. One of the nice features is that it will take a double shot at varying exposures and combine them into one photo; sort of a poor man's HDR.
I set the phone to shoot every 4 seconds for 2 hours. Be sure to put the phone in airplane mode, otherwise a text message or push notification will pause the app. Of course, the downside is you can't use the phone at all during this time.
I loaded the frames into Aperture, cropped and retouched them a bit and combined the stills in QuickTime Pro. The result is below.