Assuming that you have an irc client that works you could use
bitlbee. Just point your irc client at irc.bitlbee.org and type help and
you can set yourself up accounts on all the major messaging services. No
gateway required. Bitlbee is an irc gateway for other messaging servicesso
it takes care of what you want. Assuming you're willing to bother with
irc. I rather like it when I want to chat in text mode. Pidgin works
good in gnome but that doesn't help you on the mac. I think irssi from a
terminal should be quite pleasant if what I read is correct that terminal
reads correctly in Leopard. I have not tried it yet though as I think my
powerpc box (400 Mhz g4 with 384 MB of RAM and a slow bus) wouldn't run
it so well. There is also irssix which is a gui for irssi. I usually
use the terminal version on myboxes but then I'm a Linux geek so that
would work fine for me. If you need further suggestions I expect there
are people on this list that could help as well.
