10-31-2011 02:04 PM
First, sign up for the Beta Zone: https://www.blackberry.com/beta/
It can take up to an hour to be accepted and get your confirmation email.
Second, register your Playbook for beta: https://bdsc.webapps.blackberry.com/android/beta/b
An over-the-air update should be available for your device almost immediately.
Note: This is BETA software. It's buggy. You've been warned.