As for picking up python from c++, it should be relatively easy, the only catches are that white space is important, but otherwise I think it is a good language for rapid development. Although python can be used fro game dev, it is usually used for things like web dev and plugin scripts.
An OS can be made using C++, although the very basic low level things (like booting, ect.) are usually done with a minimal amount of C/Assembly.
A question of my own: Do you guys think the Code-In project will have an OS project?
In 90% of cases, for OSdev, you only need C and an assembly language (most probably x86). Some OSes use different languages, but they're almost always written purely so the developers can brag about having written 1337OS entirely in LOLCODE. Bare in mind that OS development is probably the most difficult area of programming to get into because you have no environment (except what you write yourself), no debugger (except what you write yourself*), and because every piece of hardware is really complicated and has to be handled differently (not just that, but also the same piece of hardware made by different companies, and not just that, but also different versions of the same piece of hardware made by the same company) because hardware engineers like to screw with programmers' heads. Even the BIOS isn't much help because practically every has a different one and every one has different bugs (BIOS programmers also like to screw with programmers' heads) that you have to take into account and work around to make your code work. Game development can be as hard if you're writing a 3D game engine by yourself from scratch (which is roughly equivalent to writing a kernel from scratch) but OS development is always hard. The advantage of OS development over game development is that you don't have to render 3D models and produce sounds, which are skills in themselves.
* emulators like Bochs and Qemu can help you here, but it's still more difficult than debugging userspace code.
I wasn't aware Vista's version of the NT Kernel had managed code in it O: I know they've been experimenting with a kernel written entirely in managed code, specifically C# and .NET, but it's still experimental.