Today Minecraft developer Mojang is launching a beta program for the Pocket Edition of its absurdly popular sandbox game. Anyone who purchased Minecraft on an Android device via Google Play is eligible to join. This will give you early access to new, experimental features before anyone else and allow you to provide feedback that could impact future versions of the title.
To enter the beta program, interested players simply need to request to join the Minecraft Pocket Edition Test Group on Google+. Once inside, they will be provided with instructions, but there is one caveat to keep in mind. Beta users will still be updated to the final version of Minecraft, and any worlds they create will work just fine with the final release. However, worlds created in the beta version may be corrupted when attempting to downgrade back to an older stable version.
Update: Here is a lengthy changelog of what to expect in the pre-release version.
Mojang is hoping to release version 0.8.0 out before Christmas, and the team reserves the right to limit the number of testers in the future if demand becomes too strong. Given the popularity of Minecraft, it wouldn't be all that surprising if they do.