The forum profile information has entries for ICQ, AIM, etc - but is notably lacking a jabber field.
Whilst I have other IM techniques, it is like a POP vs IMAP issue, I manage all IM via pidgin/finch to my jabber server, which has transports for AIM, ICQ, Hotmail, etc.
Jabber, or something darn near like it (sip based?), should be the future of IM (imnsho)
Feel free to ask the fine SMF people. It isn't anything I've disabled.