Official Yahoo! Messenger blog announced that now you can IM with IBM’s Sametime users which has ten million users same time.
To add a friend who uses Same time to your Yahoo! Messenger contact list, click the “+” button on your Messenger window. Then enter your friend’s email address and choose the “Lotus Sametime” network from the drop down menu.
As you know Yahoo! Messenger meet with Msn Messenger last year and now with IBM’s Sametime, i think soon they will migrate with other IM programs like aim, icq and may be gtalk