I really like GAIM as an IM client, but some of the functions are a bit hidden.
To get a multiuser chat going in MSN isn't as obvious as it could be. It's not hard to do, but it is a little obscure :)
Is there a way to invite more than one person to an MSN chat?
Yes. Right click a buddy on your list and choose "Initiate Chat". In the conversation window that appears, choose "Invite" from the "Conversation" menu to invite another user. When the conversation framework gets another rewrite, it is possible that this will be simplified.
From the official GAIM FAQ
