Reuters has linked its instant messaging system to MSN and AOL.

The London-based news and financial information provider said users of version 5.0 of its Reuters Messaging platform can communicate directly with MSN Messenger and AOL Instant Messenger subscribers.

This means that Reuters Messaging users, of which there are 300,000 registered and 30,000 active, will have the potential to communicate with some 200 million people worldwide on MSN and AIM.

The company also said it was in talks with other public IM providers such as Yahoo, Skype and Google and expected similar deals with them shortly.

The announcement is aimed primarily at users in the financial community, who have a pressing need for IM but who are also obliged to record all messages for compliance purposes. As a result of the new agreements, all messages between Reuters Messaging users and MSN or AIM subscribers will be archived and susceptible to search for the purpose of audit trails.

However, the move by Reuters has still wider implications, in that it takes an important step toward complete IM interoperability.

This is clearly the desire of all users, but the providers of both public and corporate IM systems have been slow to respond, valuing instead the ownership of the customer that proprietary protocols have so far made possible.

Changes are afoot, however, thanks to competitive pressures and the entry of new players like Google and Skype.

Microsoft and Yahoo have recently announced interoperability plans, while Reuters preceded the latest announcements with an interoperability deal with IBM, which leads the market in corporate IM with a Lotus-based offering.

For Reuters, the announcement is clearly a move to stay ahead of archrival Bloomberg, which offers no such interoperability with public IM networks in its IM product at the moment.

The UK news giant has plans for collaboration technologies beyond IM, too. Reuters Messaging is itself based on Microsoft’s Live Communication Server (LCS) and the company said it plans to make it possible for enterprises using that real-time collaboration suite internally to link with the financial network built around Reuters Messaging next year.