Yahoo! and Microsoft have announced an agreement to connect users of their consumer instant messaging (IM) services on a global basis, forming what they claim is the largest IM community on the planet.

The industry’s first interoperability agreement between two rival global consumer IM providers will give MSN Messenger and Yahoo! Messenger users the ability to interact with each other, forming what is estimated to be a more than 275 million strong user community.

Being able to instant message between IM communities is one of the features most requested by MSN Messenger and Yahoo! Messenger users and has been identified as a weakness of proprietary IM systems. In addition to exchanging instant messages, consumers from both communities will be able to see their friends’ online presence, share select emoticons, and add new contacts from either service to their friends’ list, as part of their free IM service.

The move by Yahoo! and Microsoft is being viewed by many market pundits as a pre-emptive strike by both companies against Google which has shown a remarkable capability to wiggle its way into most of the internet communications arenas but has yet to establish itself in IM.

Yahoo! and Microsoft plan to introduce the interconnectivity capabilities in their IM products to customers around the world in the second quarter of 2006.

“Yahoo! and Microsoft share a commitment to providing the highest-quality experience possible for consumers, and today’s groundbreaking announcement underscores our desire to provide consumer interoperability between our thriving IM communities,” said Terry Semel, chief executive officer, Yahoo! Inc. “This is truly a turning point for the IM industry, and we believe our agreement with Microsoft will help usher in a new era of IP communications.”

“Microsoft and Yahoo! look forward to bridging the divide between our global communities, creating richer and easier ways for our customers to connect,” said Steve Ballmer, chief executive officer of Microsoft. “IM interoperability is the right thing for our customers, our businesses and the industry as a whole, and Microsoft is delighted to help lead these efforts with Yahoo!”