I\’ve beet fighting with the CP1251 char encoding to work with Kopete ICQ for a while and finally I found how to enable it properly.
After creating the ICQ account withing the Kopete, edit ~/.kde/share/config/kopeterc and under [ICQ] part of the config change DefaultEncoding to 2251.
The problem is that CP1251 is a most used encoding for ICQ to talk in Russian and that was preventing me from using Kopete as an IM, since it had some problems with this encoding. Now everything works just fine.
BTW, I also seen some Skype plugin for Kopete, although it was still under early development.