An IM session in Facebook Messenger for Windows 7.

The messaging function built into Facebook has already replaced established IM programs for some computer users. Facebook overnight released a test version of a standalone Windows app that could give the social network an even larger presence in instant messaging.

Facebook Messenger for Windows is available for public download via this Facebook help page. Facebook went public with the download after it leaked from a private beta test.

Development of the app was led by a Facebook engineering team in Seattle, in conjunction with Facebook engineers in California. It was designed let users stay connected to the social network on their PCs even if Facebook isn’t open in their browsers.

Facebook says it works only with Windows. It includes a Facebook ticker feed and notifications in addition to IM features.

A Facebook representative said in an email: “We are continuing to make Facebook Messenger easily accessible across platforms. Messenger is available for iPhone, Android, Blackberry, and today we’re starting to test a new application for the desktop, Messenger for Windows.”

We asked about a Mac version, but company isn’t saying if there’s one in the works.

Facebook warns on the help page that Facebook Messenger for Windows is still in trial mode, noting that the engineers “will be rolling out changes to the app and expect outages and periods of instability as we make improvements.”

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