Yahoo Inc. and Microsoft Corp. are two of a number of high-profile vendors in IMUnified, a recently formed coalition trying to develop open standards-based interoperability for instant messaging.

IMUnified plans to deliver a new IM protocol for the delivery of text and the exchange of buddy lists by the first quarter of this year, according to some of its members. Other companies in the group include AT&T Corp., Excite@Home Inc., Odigo Inc. and Prodigy Communications Corp.

Some of the group’s members claim the new protocol could arrive sooner rather than later, citing contractual coordination between the companies as the biggest obstacle to timely delivery. All of the members in IMUnified plan to adopt the new protocol once all agreements are finalized.

Yahoo confirmed it would add the interoperability features adopted by IMUnified in the near future to its IM software, according to a Yahoo spokeswoman. Microsoft’s MSN subsidiary has also confirmed it will stick by IMUnified’s plans, according to Bob Visse, group product manager for MSN.

IMUnified will try to solve some of the problems users face when using IM applications. AOL dominates the IM sphere but has been reluctant to offer interoperability with other short-text delivery systems. This forces users to set up numerous accounts with differing information if they wish to communicate with others who use a different service. AOL representatives have claimed they want to ensure a user’s privacy and security before making their systems interoperable with others.

Some analysts doubt both AOL’s privacy and security claims as well as whether the company can continue to hold onto its market share lead — interoperable or not.

“Instant messaging will be incredibly widely used,” says David Ferris, president of San Francisco-based market research firm Ferris Research. “In the long term, only a minority of people will use AOL.”

Ferris predicts it will take about two years for AOL to lose its stranglehold on the IM market. While an estimated 80 percent of IM users are on either AIM or ICQ, Ferris claims the heavy adoption of IM services will tear away at the company’s market share. In addition, Ferris has no doubt that AOL will “cave in” to the interoperability demands of other IM vendors.

MSN’s Visse says his company is “all for” interoperability. “In the end, this is what customers are going to expect.” However, he voiced some concerns about taking the open approach to IM. “What happens if AOL adopts interoperability but only on a one-way basis?” he asks.