Python is a very good choice for making game draft, because you can write quite complex code very fast. But you'll end up with a very slow game, because Python is a scripting language (it's not compiled to bytecode). So you'll want to rewrite code which is critical for perfomance in C/C++/Delphi (definetely not Java
) to produce fast bytecode.
Python is a great choice for built-in scripting language. Civ IV will use it, and it seems it'll kick se4's (and probably se5's) *** in terms of modability.
So use it for small lightweight projects, not big and resource-consuming ones. Use it to write game draft or to embed it for scripting purposes.