After a failed launch attempt a few weeks ago, BlackBerry has finally brought its BlackBerry Messenger (BBM) service to competing platforms.

The company announced today that the BBM apps for iPhone and Android are now available — though not everyone will be able to start chatting immediately.

In a move meant to stem the tide of potentially server-crashing traffic, BlackBerry is at first only allowing access for the six million people who signed up for information about the apps at Everyone else will have to wait in line. If you didn’t sign up at, you can claim your spot in line by downloading the BBM iPhone and Android apps and plugging in your email address.

BlackBerry Messenger is one of the company’s few remaining success stories, with more than 60 million active users. It rose in popularity among the BlackBerry faithful thanks to its fast messaging capabilities, but now it faces stiff competition from other cross-platform chat solutions like Kik and Tango.

The BBM launch follows the leak of an early version of the Android app, which brought RIM’s messaging servers to their knees and led to the delay of the official BBM apps. Right after the BBM launch fiasco, BlackBerry accepted a $4.7 billion buyout offer from Fairfax Financial Holdings, a Canadian firm known for taking on troubled local companies. (Recent rumors also point to Lenovo showing interest in snapping up BlackBerry.)