borismus.com
Seriously, though it's a simple idea I agree with some of the blog commenters - this has real commercial potential. You should protect the IP in some way even if your plan is to keep it open source, so someone else doesn't patent troll the idea. Also, seeing as how it's winter, now about a version that goes down your sleeves and plugs in to a pair of gloves or mittens, making everything into a drumkit?
Lots of luck with this - it's a little crazy but in a cool way. Inexplicably, it reminds me of those shoes with rollers in the heels...not exactly useful, but so much fun that that it's irresistible.
one features a drumset: http://www.thinkgeek.com/tshirts-apparel/interactive/ac0b/
and the other has a guitar you can strum: http://www.thinkgeek.com/tshirts-apparel/interactive/c498/
The negative part about them is that the gear is not extrudes a little bit from the shirt itself.
BTW, if you're interested in doing this sort of thing -- 2-wire piezo buzzers from radio shack make good velocity sensitive sensors. I built an electronic drumset out of PVC pipe and plywood and taught myself how to play drums with it.
You can play with materials a little for the surface -- I used plywood and mousepads. Mousepads are a little soft (the traditional 3/8" thick foam rubber with a cloth backing type...), Different thicknesses of plywood affect sensitivity, etc. If there isn't enough mass, false/double triggering happens.
It's a fun thing to try, and the materials are really cheap (and there are DIY drum trigger boards you can find on the internet now...)
Hell, slice one of those roll-able keyboards in half and bond them to the garmet.