MSN and Yahoo! messenger had signed up a deal to allow messages across their networks. And finally it seems like its really possible to do it. I had read about it on digg around a week ago, but at that time it was possible to do it using Yahoo! Messenger for mac. But now it is working for the windows version of Yahoo! Messenger. Here is a screenshot of the messages across the two networks.
As of now the speed seems to be a problem. It takes more than a minute to get a message across. But then again its just a beta and its like the first week, so these problems would exist in any case. I am waiting for the day when I can finally uninstall one of the IM's. I have always liked Yahoo! Messenger but Windows Live Messenger matches in most features now. So now its more of a personal choice rather than the number of features that each IM client provides.