In published reports (Yahoo declined to answer our requests for an interview by press time), the company is quoted as saying it intends to use changes to its IM protocols to block spimmers from accessing its network, and has vowed to continue making changes to restrict third party access.

At variance with most reports, however, is the extent of the block. While Trillian's chat client, which allows access to multiple networks (such as those maintained by AOL, Microsoft, ICQ, and Jabber), might be the most prominent victim of the protocol change, it has also cut out users of such clients as Adium and Fire on the OS X platform, gAIM on Linux and Windows machines, and CenterICQ.

Additionally, a workaround posted on Slashdot, in which users can change the host with which their IM clients attempt to connect to Yahoo's servers, appears to work only for Trillian users.

The uneasy relationship between IM providers and third parties who try to provide alternate access to their networks is nothing new. In 2001, AOL drew the ire of the Open Source Jabber project when it made protocol changes that blocked Jabber users, who depend on gateway software referred to as "transports," from access to its network. Since then, AOL, Yahoo, and Microsoft have all variously blocked or disabled access from third party clients and servers through undocumented protocol changes or simple client blocks.

There is, however, little incentive for the providers to allow access to their services. As Radicati Communications Director Genelle Hung said in a recent interview, the current balkanized state of instant messaging has produced "a whole bunch of winners" with no incentive to work on interoperability.