Hm, it seems that I have found a little bug with the telepathy-butterfly plugin (using my N900):

If you go into the address book profile (through address book or via a shortcut) to someone with MSN, you can see the MSN logo and their MSN email. After you have started a session and talked with them, you close the window.
If you go into their profile again, the MSN field is gone but they still show up as online/green. The only way I can contact them again is going to the menu and to the Conversation app, where I have to pick up the old conversation.

I rebooted the device, and the MSN email/icon appeared in the address book profile again (and they was still in the conversation app). As soon as I pushed the MSN field and said something, closed the box and went back to the profile the MSN field was gone again...

This does not happen with skype/google talk.
Do anyone other than me experience this?