Research in Motion has released an update to the Playbook’s OS, giving the tablet support for tether free e-mail and some Android applications.

“Building on the BlackBerry PlayBook tablet’s proven web browsing, multimedia and multitasking strengths, the new BlackBerry PlayBook OS 2.0 introduces a range of new communications and productivity enhancements as well as expanded app and content support,” said David J. Smith, Senior Vice President Mobile Computing, Research In Motion.

In addition to a new e-mail client and support for some Android applications, the refreshed OS promises better social integration with the calendar application, as well as an updated BlackBerry bridge app.

The lack of built in e-mail client led to a number of negative reviews when the Playbook first launched last April. During the Playbook’s launch quarter, RIM only shipped 500,000 units; during the quarter that ended November 26 the company shipped only 150,000.

Apple shipped 15.4 million iPad’s during its most recent quarter.