WinBreak writes "Marketwatch is reporting that, nine months after their announcement, Microsoft and Yahoo! are finally ready to roll out beta IM clients of MSN Messenger and Yahoo! Messenger that will be able to talk to each other." The Windows Live Ideas and Yahoo! Messenger pages have more information; the companies say that the resulting user community will be the world's largest, at around 350 million accounts, and that they'll be using SSL to encrypt the traffic between the systems.