As expected due to the app having arrived on the Windows Phone Store under private beta status, BlackBerry has now announced their open, external beta for BBM on Windows Phone. As noted on the Inside BlackBerry Blog, BBM on Windows Phone will bring a fresh new native look & feel having been specifically designed for Windows Phone.

The BBM team here at BlackBerry has been busy getting BBM for Windows Phone ready to go. We're preparing for an external beta ahead of our launch and are ready to start accepting applications to participate. Now remember, this is a beta and our expectation is that participants will help us make BBM for Windows Phone great by actively participating. If you're not ready to report bugs, respond to surveys and provide feedback – better to wait just a bit longer for the full release. If you are excited to join the BBM for Windows beta program, please apply at BlackBerry BetaZone.

Out of the gate, BBM for Windows Phone won't have stickers, BBM Voice, BBM Channels and location sharing powered by Glympse but all that good stuff is being worked on and will be added as the app progresses. If you've got a Windows Phone kicking around, you might want to sign up when the links fully go live or at the very least, tell folks you know about it!