[photon]

Well for example if you want to write a Windows C++ app, the IDE is irrelevant because the compiler is what links and compiles.. so if you can write iPhone apps on Windows that would mean the compiler and linker and all the necessary libraries are there in Windows... but I guess it would be a different compiler than a normal C++ compiler and that compiler would probably be closely tied in with VS (not a command line compiler) so I guess I'm probably wrong in thinking that one could create an Eclipse plugin.

As for C# or VB to write the iPhone apps, they definitely could restrict that. When you write a C++ app in VS you can specify what kind of app you want to write. A "real" C++ app that compiles to real machine code, or a managed C++ app that uses a different compiler to compile the C++ code into bytecode for the .NET runtime.

I would assume that the compiler that would compile down to iPhone native code wouldn't be able to parse or compile C# or VB code.