Facebook is going into direct competition with instant messaging services from companies such as Microsoft and Yahoo by launching its own, web-based IM service, Facebook Chat. Though the release is limited at this time, Inside Facebook was lucky enough to get a look at the service calling it “a great implementation” that’s sure to pose a threat to legacy IM networks.

Facebook Chat takes a page out of Gmail’s GTalk feature by building the web-based IM service directly into the site, through an always-present chat bar at the bottom of every page that gives you access to your current chat windows, online friends list, notifications, chat settings, and online status. It also offers a way to pop-out your conversation windows, so you can continue browsing Facebook without losing track of your chat session. Check out a short review here, and expect the new feature to be widely available within the next few days.