We’ve seen a few hacks to enable multitouch in Android; my experience with the HTC Hero, which enabled it, was that hardware support is only half the issue. You also need the software to support it in order for it to be of any use: on the Hero, that meant the browser would recognize pinch-zoom but the Google Maps app would not. That’s a breakdown in UI consistency, which usually leads to user confusion.

Multitouch is already usable in Android SDK :

http://www.alicesbiscuit.com/android-sdk-multitouch-workaround.html

Hope that helps