WindowsPhoneHacker have updated his home brew Orientation Lock app, which, as the name suggests, disables the accelerometer on Windows Phone 7, allowing one to read your email in bed easily for example without the screen constantly flipping.
The updated app now, besides bug fixes and optimizations, features a secondary live tile which can be pinned to your home screen and which acts as a quick toggle for the functionality of the app.
If you tap on it the application will fire up for about half a second, then close and take you back to start.
Orientation Lock v3 need a developer unlocked handset, but not Interop unlocked, so should be accessible to the 100,000 registered app developers .
The XAP is free and can be found on WindowsPhoneHacker here.