The Android SDK is indeed available, but only in private alpha, as it's not yet ready to share with the broader developer community -- there are still some hurdles that we need to overcome before it can be useful for beta development. As a result, we have to be somewhat selective in sending it out, so that we can provide the appropriate level of long-term personal support.
To apply, you can drop us a line at developers@leapmotion.com with a brief proposal including what you intend to build with it, and what you've built in the past