The Go Pro HD Hero is one of the best timelapse cameras out there for 24 hour imagery, its wide angle lens, the ability to power via USB and mount on an outside facing glass window via its suction cup makes it easy to set up and leave.
The camera copes well with changes in light, the movie below was captured using the default settings with the images processed in QuickTime (version 7). The main restriction is memory card size, we have used the Go Pro to capture a view across London over 12 hours, with one photograph every 5 seconds it amounts to almost 16gb of imagery:
In similar manner for the timelapse below we mounted our Go Pro HD Hero on an outside window and pointed it towards the sky. The movie consists of 10,863 images captured one every 5 seconds:
With the increasing availability of timelapse apps on Android and iOS it is possible to capture and automatically output a timelapse in HD quality, the only problem is mounting and waterproofing, making the HD Go Pro Hero still the best choice for urban timelapse movies.