A new jailbreak-like app has snuck its way into the Apple App Store. Bluetooth OnOff allows you to activate or deactivate your bluetooth just by launching the app. This is much better than having to go to Settings/General/Bluetooth/Toggle to switch your bluetooth on and off. However, the app does access iOS settings which is a violation of Apple's app guidelines. This means it will probably be pulled.
You can download the app for $0.99 in the iTunes App Store while it's still available. Bluetooth OnOff is compatible with the iPhone and iPad. It requires iOS 4.1 or later.