Interesting concept. Just tried Xylophone app. Tap-recognition is microphone-based. Unfortunately, it's not very accurate at the moment.
Wondering if sound+accelerometer would help to make a better mobile seismometer :)
WHAT IS THIS BLACK MAGIC!??
But seriously, this is neat. Reminds me a little of SnowShoe Stamp (cc'ing its founder, @CCMoberg) in that it could be applied to many use cases. Curious to see what creative ideas people (particularly game designers) come up with once its SDK is publicly available.
Domino Spot