Research in Motion has made BlackBerry PlayBook OS 2.1.0.840 Beta available to developers, or, really, any BlackBerry PlayBook owner that wants to download it.
BlackBerry PlayBook OS 2.1.0.840 Beta features include:
Runtime for Android apps
Adobe AIR 2.x
WebWorks
Native API 2.x
You do have to jump through a little hoop and register your BlackBerry PlayBook for Beta access before you can download the latest OS, however, doing so is a straight forward process that can be done at the following link:
https://developer.blackberry.com/devzone/register