Possible Duplicate:
How to programatically take a screenshot on Android?
How to capture the android device screen content and make an image file using the snapshot data? Which API should I use or where could I find related resources?
BTW:
not camera snapshot, but device screen
According to this link, it is possible to use ddms in the tools directory of the android sdk to take screen captures.
To do this within an application (and not during development), there are also applications to do so. But as @zed_0xff points out it certainly requires root.