Cygon4:

I remember reading somewhere that the C++/CLI generated som MSIL opcodes that the compact framework's CLR didn't understand

There are two unrelated issues here:

1. Does code compiled using language X run on the Xbox 360 Framework?
2. Does the IDE for language X support the XNA Framework?

The answer to question 1 depends entirely on the language. The FAQ ZMan linked to lists the answers for many languages. Some work. Some don't. Others kind-of work if you are careful.

The answer to question 2 is much simpler. Today:

    if (IDE == C# Express)
           yes
    else
           no

Coming in version 2:

    if (IDE = C# project loaded into any flavor of Visual Studio)
           yes
    else
           no

In other words, we are only doing IDE work to integrate the XNA Framework into the C# project system, and not currently supporting the project systems for any other languages. In the absence of this IDE work, you miss out on exactly two things:

• Content pipeline integration
• The ability to deploy and debug on Xbox 360
  

Now, you may be just fine without those things. Maybe you're making a Windows game that doesn't use the Content Pipeline. In that case you don't care about our IDE integration, so the lack of it will not hurt you, and you can use any .NET langauge you like.

If you want to use the Content Pipeline, or deploy to Xbox, you can still do that by building your other-language code into an assembly, then using a stub C# project that links with this assembly to build your content, deploy to Xbox, and then call into your real assembly as soon as it starts up. It's a hack, but some people have reported success working this way.