The version currently installed on Athena is 1.5.0 with a couple of fixes for connecting to MIT's jabber server. For more information, on gaim, you can go to http://gaim.sourceforge.net
To run it from any Athena cluster workstation, type
gaim
On some older Athena workstations, gaim is not installed locally, and you will have to run an older version from the im locker. To do that, type
add im; gaim