Facebook Chat, the company’s instant messaging system, has already been live on other sites, like Meebo, for more than a year. But now it’s coming to the granddaddy of IM: AOL’s AIM. Starting now, you can log in to your AIM account — whether your use the Windows or Mac desktop clients or the web-based version — then log in to Facebook using Facebook Connect.

You’ll just need to click through a couple Connect permissions windows, then you’ll see your Facebook friends appearing within your AIM interface — sort of. As of right now, there seems to be a bug, because no Facebook users currently appear to be logged in to Chat from within our AIM interface even though those same people are currently online on Facebook. New software tends to be buggy and we expect this problem to be fixed shortly.

Overall, the use of Chat looks good. If you’re one of those Facebook power users who has sorted their friends into lists, you can see which friends in each list are on Chat, basically like you can on Facebook.

IM is not the only Facebook integration here, even though it’s the most significant. AOL has been working on various versions of what it calls “Lifestream,” for years. The feature, which has gone through a number of big changes, is intended to be sort of like FriendFeed, or Facebook’s news feed, or Google’s new Buzz, in that you can share and respond to your and your friends activity on other sites from within it. Lifestream has let users both see Facebook status updates, photos, etc. from their friends on Facebook as well as update their Facebook status from AIM since last September.

It’s not clear how popular Lifestream is at this point, but AIM is still used by tens of millions of people. The big idea is that AOL is trying to be more open than it has been over the last decade. “We are now taking risks that historically we would not have taken,” Brad Garlinghouse, president for Internet and mobile communications at AOL, tells The New York Times. “People who use AIM are much more likely to use other parts of the AOL experience. So for us we are looking at creating a more useful product. This is about getting back to basics.”

Strategically, as AOL seems to be hoping, AIM users could choose to use Chat from within AIM instead of ditching AIM for Chat on Facebook. If this proves to be the case, the Chat integration could bring more users to other AOL features, like Lifestream. Not a bad idea. Meanwhile, as PC World points out, many other companies have long offered ways for users to IM with friends across AIM, Chat and many other IM providers. These services are probably a better fit for serious multi-platform IM users. Besides Meebo, they include Digsby, Pidgin and Adium.