In my Android app I enable my specific app-search to be triggered via the search key in a number of my activities using this mechanism from the manifest
This has been done specifically to circumvent patent issue. This has been mostly done only in USA, where apple recently got an injunction on galaxy nexus. So all Android phones in USA will show this behavior from now on. So most of the apps in jelly bean have a on screen search button.
If you have a cyanogenmod based phone (e.g. jellytime for HTC DHD like me), the old behaviour is only a setting away:
Menu/Systemsettings/System/Hardware keys/Search/In-App-Search
But this change wasted quite some of my time for debugging my app and researching to find this solution. Needless to say I hate patents, especially ridiculous ones: obvious behaviour like an OS sending a hardware key event to an application can be patented???