I was just wondering what language would be a good choice for developing a game server to support a large (thousands) number of users? I dabbled in python, but realized that it
You could as well use Java and compile the code using GCC to a native executable.
That way you don't get the performance hit of the bytecode engine (Yes, I know - Java out of the box is as fast as C++. It must be just me who always measures a factor 5 performance difference). The drawback is that the GCC Java-frontend does not support all of the Java 1.6 language features.
Another choice would be to use your language of choice, get the code working first and then move the performance critical stuff into native code. Nearly all languages support binding to compiled libraries.
That does not solve your "python does not multithread well"-problem, but it gives you more choices.