The home hard key toggles between the app tray and the home screen. Mine does not work anymore. I did a "wipe data / factory reset" still no good. The link below will explain what I'm talking about. Any ideas?
http://motorola-global-portal.custhelp.com/app/answers/detail/a_id/48579/kw/home%2Bkey/p/30%2C6720%2C7500%2C/session/L3NpZC9XaER0WG41aw%3D%3D/p_country_code/US/p_reference/moto_integration.php
Motorola support didn't know abything. I think the firmware update deleted this shortcut.
"Press Home to open your App tray, and also to close any menu / app and return to the home screen".