Snappy is a new iPhone utility by Marc Vaillant which lets you snap photos from any open application

Never miss a photo opportunity again! Snappy is a camera app for the iPhone that launches and is ready to take pictures in one second, without having to exit your currently running application. Snappy is also accessible directly from your lock screen. Simply tap and hold the status bar (the bar at the top of the screen with AT&T logo, signal bars, battery, etc) to launch and you are immediately ready to take pictures; compare that to the five to six seconds it takes to exit a running application and launch the native camera app.

You can download and purchase Snappy from the Cydia Store for $1.99.