you are going to have to compile from source unless there is a current binary in your apt cache, try this do an apt-get update then an apt-cache showpkg gaim look at the top and it should tell you what versions are avialable on the repositories in you apt.sources list. I you see .64 you should be able to get the newest version. If not I would recommend compiling from source, I have compiled gaim before and its pretty simple and quick. Either way .64 is the newest version so if you can't find a .deb package (these are debians package, sourceforge only provides .rpm for gaim it seems) then you will need to compile it, but it seems here that ftp.debian.org has the newest ver so apt-get install gaim should work (It worked for me, im using .64 but I also did an apt-get dist-upgrade so I may be running newer libs)