The GTalk outage gave me some time to run another test of pidgin vs. kopete in memory consumption. Pidgin used to always win this competition, which is - next to the then better working file transfers - why I use pidgin.
I tested it again today and this time the Kopete coming with KDE 4.1.1 in Kubuntu won!
- Kopete used about 18 MB ram
- Pidgin used 23 MB ram
These results and the differences were reproducible. They were tested with "free" in the console. I started one program, then the other and in between ran free in the shell - several times.
Of course these results apply only if you're running a KDE 4.1.1 desktop. If you're a gnome user, pidgin is very likely to use less memory for you.
Also reproducible was that Kopete ate a lot of memory when opening the - currently very slow - configuration dialogue.
There seems to be a bug somewhere, as this memory is not freed until after you restart kopete. So after configuring something in Kopete 0.60.1 make sure you quit and restart it.
Feel free to test it yourself and post your results. Make sure to include what distribution, program versions and desktop environment you use and that you have the same amout of accounts active in each program.