Research in Motion announced Tuesday that it has released an upgrade to its BlackBerry PlayBook operating system, finally bringing a native e-mail client to its 7-inch tablet after nearly a year on the market.

In a company blog post, RIM’s senior vice president of mobile computing, David J. Smith, said that “the features I’m most excited about with this launch are built-in email, calendar and contacts.” The e-mail client has a unified inbox, but the operating system still lacks some of the functionality you might expect from BlackBerry. The PlayBook still has no access to BlackBerry Messenger, RIM’s instant-messaging service.

RIM also made some modifications to the BlackBerry Bridge application, which lets users’ smartphones and tablets communicate with each other. Thanks to a new feature introduced in this update, PlayBook owners should be able to use their BlackBerry phones’ keyboard and navigation for the tablet.

The update also includes support for some Android applications, which could conceivably help the company with the app problem I outlined in my initial review of the tablet last year.

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