launch/start an App (Activity) by a gesture on the homescreen is it possible in Android(>= 3.0) to launch/start an App (Activity) by a gesture on the homescreen. For example: if the user swipes from the bottom to the top on his homescreen, then App XY should be started.

Thank you
You can install a third-party homescreen (launcher) app which supports gestures. Some examples: Holo Launcher HD, Apex Launcher, Nova Launcher. Note that such gestures will work only when the launcher is active (i.e., they are not global gestures accessible from any app), and may be eaten by scrollable widgets if they are present at the homescreen, and you start the gesture inside such widget.

Globally accessible gestures are possible too (e.g., there are apps such as SwipePad), however, this will increase resource consumption, because such app must be running all the time and listening for touch events, and also may conflict with other apps.