Reuters is working down its checklist of the major instant messaging systems, announcing Monday that it has added Microsoft's MSN Messenger to the list of IM services that will be supported by the next version of its Reuters Messaging software, expected early next year. \n\nReuters\u00a0is working down its checklist of the major instant messaging) systems, announcing Monday that it has added\u00a0Microsoft's\u00a0MSN Messenger to the list of IM services that will be supported by the next version of its Reuters Messaging software, expected early next year. .The Reuters Messaging system is the first with which Microsoft has agreed to link, allowing users of the two different services to exchange messages. Other interoperability deals are under consideration, according to a Microsoft spokesman.Reuters unveiled earlier this month a connectivity agreement with AOL covering the AOL desktop, AIM and ICQ services. It also has a testing arrangement with IBM, whose IBM Lotus Instant Messaging system (formerly Sametime) is expected to be added to interoperability list in Reuters Messaging's next update, due in the first quarter of 2004.AOL, Microsoft and Yahoo are the IM market leaders, together controlling hundreds of millions of user accounts. Reuters is a comparatively small player, attracting 50,000 active users to its year-old service. Reuters Messaging is aimed at financial-services workers, offering security, logging and auditing features to help companies comply with legal and regulatory mandates.Reuters could pull off a connectivity trifecta: A company source said it is in discussions with Yahoo and hopes to soon add Yahoo Messenger to its network of supported systems. In the highly politicized IM market, no company has yet managed to arrange official interoperability deals with all of the major vendors, leading frustrated users to turn to renegade solutions such as Cerulean Studios' Trillian software. Trillian aggregates several IM systems, offering access to them through a single software client.Microsoft's selection of Reuters as its first connectivity partner isn't surprising, given the close ties between the two companies and their technology. Reuters Messaging is built around an early version of Microsoft's forthcoming Live Communications Server. Reuters' collaboration services head, David Gurle, previously worked at Microsoft overseeing the development of its Live Communications Server software. He joined Reuters in March, several months after Reuters Messaging's debut.Reuters Messaging is currently available for free, but some users will have to begin paying after the upgrade to receive features including AOL and Microsoft IM connectivity, according to Reuters spokesman Kyle Arteaga. Reuters' desktop software clients will receive the upgrade for free; others will be charged a yet-to-be-determined, per-user fee, he said. Reuters software products offer news, market information and trading tools.Financial terms of the deal between Microsoft and Reuters were not disclosed, but Arteaga said the arrangement includes payments calculated according to the traffic volume between the two systems."It's very similar to the way the telecoms work, with a network usage fee, based on whose system is bearing the load," he said.