Open AIM, as the initiative will be known, is being launched because there are a lot of developers out there who can take advantage of this in ways we may not get into ourselves, according to director of product management Jamie Odell.

Developers who want to build AIM connectivity into existing applications, create new presence-based instant messaging, VoIP and video clients, integrate AIM presence into web sites, will be able to do so free of charge, according to AOL.

There are a number of restrictions, however. Not least of which is the fact that it’s only free to use in consumer applications. If a company wanted to build AIM into an enterprise application, they will have to take out a license with AOL.

In the consumer space, if an application built with the Open AIM toolkit is being used for more than 250,000 logins per day, or over two million per month, then the developer will have to seek out a commercial license with AOL.

There’s also a blanket ban on multi-headed IM clients, according to Odell. You couldn’t legally use Open AIM to make a client that connects to both AIM and MSN Messenger or Google Talk networks, for example.

So, even if it allows developers to tap into a community of 63 million users, it’s not completely open.

There are three components to the initiative. An SDK that enables the creation of plug-ins for AIM Triton, the current version of AOL’s client, an SDK for creating standalone clients, and a web service for integrating AIM with web sites.

According to AOL, an early example of software built with the toolkit can be seen in AIM Pro, a version of AIM released with WebEx Communications Inc recently.

It’s a bit of a switch of direction for AOL, which is not known for its developer outreach, but it may have been driven by competitive pressures as much as anything else.

The company has long been the leader in the consumer instant messaging space, but a promise last year by Microsoft and Yahoo to link their respective networks threatens to bump AIM down to second place in terms of number of users.

Meanwhile, Google’s recently introduced Google Talk was designed from the start to be interoperable with other Jabber-compliant servers, and Google makes the documentation available to help developers link up.

AOL has agreed to talk to Google about interoperability between AIM and Google Talk, as part of the $1bn deal last December that saw Google take a 5% stake in the Time Warner Inc subsidiary.

Odell said that interoperability talks are continuing. The deal called for interoperability provided certain conditions are met, but those conditions have not been disclosed.

AOL said that security considerations have been taken into account with the launch of Open AIM. Each developer will get a key they have to embed in their applications. Abusive software will be blocked, Odell said.