Version 1.2 of Google Gesture Search was announced yesterday. The new version contains a new feature that lets you flip your phone to start Gesture Search. According to Google, "this eliminates the need to activate Gesture Search from a home screen shortcut." Sensitivity can be adjusted in the applications settings.
I did play with it a few minutes ago. So, in the settings you have the option to Disable, Hard to trigger, normal and easy to trigger. After a few seconds trying it, I've configured the "Double Flip sensitivity" to Disable.
See Double Flip at work: