Nokia N900 Application: Camkeyd

CamKeyd is a application for the Nokia N900 (Maemo 5) that allows the camera button to be used to quickly access Task switcher. Use the camera button (focus, i.e. half-pressed) to access Task Switcher when the lens cover is closed. Useful with fullscreen applications. No configuration, simply install to enable and uninstall to disable.

Download the app from here