The version gives Linux fans a sanctioned way to join their Windows and Mac OS colleagues on the popular AIM chat service.
"As we expand to multiple platforms like Linux, we're making sure we meet their needs," said spokeswoman Jane Lennon. AOL doesn't have a specific schedule for releasing a final version of the software, she said.
The move highlights the increasing legitimacy of Linux, a clone of Unix mostly used on heavy-duty server computers but increasingly popular as a desktop operating system.
Linux, though generally requiring more technical skill to use than Apple's Mac OS or Microsoft's Windows, provides computer makers a way to build devices for connecting to the Internet without licensing Microsoft software. Companies such as HelixCode, Corel and Eazel are working to make Linux easier to use.
Even before AOL got into the act, people who used Linux had ways to connect to the AIM service. For example, Jabber offers instant messaging software that works on Windows and Linux computers and also on others through a Java client interface. Corel Linux ships ready to work with Linux through the Java client.
Another program, called Gaim, also can tap into AIM services, Gaim co-founder Rob Flynn said in an interview today.
Adding a Linux client for AIM makes sense for AOL as it embraces a variety of new devices to tap into its services.
In particular, AOL, in partnership with computer maker Gateway and chipmaker Transmeta, is developing a line of easy-to-use appliances running Linux to connect to the Internet and AOL services. These Internet appliances are due later this year.
AOL increasingly is concentrating on software development. The company is working with Gateway to develop applications for Net appliances, Gateway CEO Jeff Weitzen has said. For example, a kitchen countertop appliance might contain favorite recipes or links to e-commerce grocery sites.
AOL also is developing a Linux version of software called Gamera to connect to AOL services.
Though AOL has spent much time making sure other instant messenger software can't connect to AIM, the policy doesn't extend to everyone.
"We don't authorize attempts to use our software or systems without our permission," Lennon said. AOL's policy is based on its effort "to protect the privacy and security of our members and users."
Gaim's Flynn said he and his fellow programmers use a basic version of the AIM communications protocol called TOC. The organization is testing another version that uses a more complicated protocol, the one used by AOL's own software, called Oscar. That protocol allows two chatters to connect directly, cutting the AIM server out of the loop.
"Our Oscar support is still experimental," Flynn said.
Gaim and his colleagues figured out the TOC protocol based on an open-source AIM client AOL released about a year ago called TiK, Flynn said. Because the software was released as open source, anyone could take a look at how the program worked.
AOL has a crushing lead over instant messenger services offered by competitors, which include Yahoo and Microsoft, among others. AOL counts 61 million screen names among people who have downloaded its AIM software, not including its 23 million paid subscribers who also have access to the service. In addition, AOL owns ICQ, which counts 70 million downloads.
AOL has so far refused to allow people who use competing services to connect to its network, citing security concerns. But the company has said it welcomes interoperability and will cooperate in establishing protocols for a common IM standard.
Microsoft, among other companies, has submitted proposals that will be considered in drafting final recommendations for the standard.
Flynn and fellow college students started the Gaim project in 1998. Flynn now works at TGF Linux Communications.
News.com's Michael Kanellos contributed to this report.