I just put the app on my phone and it does work. I'm sure there will be better one's along soon, but right now, this one is free AND it works. The mic is super sensitive. I haven't tried it outside yet but I'm sure wind noise would set it off. Even with the sensitivity cranked up it would register small taps and even just clicking the camera button on the side. However if you muffle the mic with say a sock, it works great. Can't wait to try it live.
Link : http://forums.somethingawful.com/showthread.php?threadid=3178008&pagenumber=2
Give it a try, and let him know what you think.
Zero