RIM’s BlackBerry PlayBook product manager, Michael Clewley, has confirmed through his Twitter page that the company is planning to release a beta version of its 2.1 Playbook OS by the end of May.  After taking a role as a BlackBerry developer, the update will be pushed to eligible devices once it is released.  RIM’s prior update brought native contacts, calendar and email to the tablet. Details surrounding the PlayBook OS 2.1 beta are not yet available.