Probably not.
What they added, I am guessing, is a database of userIds with an association of other userIds that are potentially interested in communicating with this user. When you start you Instant messenger program (however that's done) they notify all other Instant messenger programs of users that are interested in you and at the same time let you know of all the users you are interested in and happen to be On (i.e. have their Instant messenger program running) at the time. The database with userId status is maintained in real time. This is different from you seeing who is logged in and then sending them a message. The actual mechanism of sending of the message is probably (I don't know!) not part of the patent.
Alex
"No man's life, liberty, or property are safe while the legislature is in session."\t-- Mark Twain