AOL has finally opened its hugely popular AIM chat network to third-party access. This is great news for developers and users alike because it will make things run much more smoothly over multi-service chat applications. These applications are free or shareware programs that allow users to sign on to many services at once: gTalk, AIM, Yahoo, and MSN, for example.

I personally use Adium on the Mac and have never been able to get the file transfer feature to work on AIM. That’s because in order to send messages over AOL’s service, developers have had to reverse engineer and otherwise hack around the unknowns, leaving everything but the basics open to failure.

In addition to the open network and the access to added features, AOL is also promising to integrate AOL-served ads as part of a revenue sharing plan. Details there are still forthcoming.