According to Wikipedia, Mono has three main components:
I want to know what the language or technology each one of those components is developed in.
EDIT:
I know that the some portions of the project is developed in C#, especially the old ones, but I want to know if the WHOLE project is developed in C#, or not.
mono is open source - why don't you just look at the source? see here http://www.go-mono.com/mono-downloads/
Edit: To be less rude
One of the first things mono did was to build a self compiling C# compiler. I would assume that they still write most of the stuff in that or a direct descendant.
Here's a link to the Mono Subversion repository. From The Compiling Mono From SVN:
This assumes that you have a working mono installation, and that there's a C# compiler named 'mcs', and a corresponding IL runtime called 'mono'.
So I guess it is implemented in C#
The Mono compiler (mcs/gmcs) is written in C++.
The class libraries (System, System.Web, etc.) are written in C#.
Some of the low-level functionality that can't be done in C# (for example: P/Invoke, native windowing) is also written in C++.
This is a educated guess, but the vm, jit and all the runtime stuff is probbly written in c or c++. The development stack like the interfaces to gnome api's, language libaries etc are probbly written in c sharp.
Microsoft compatibility stack is probbly written in c sharp implemented with the c sharp interfaces to native linux libaries.
It is a guess though. You can check yourself.
The runtime itself is written in C. The different class libraries and tools, as well as the C# compiler are entirely written in C#.
The only exception is the VB compiler and VB libraries that are written, well, in VB.
You can see a breakdown of lines of code in individual languages here.
The core itself which has to communicate with lower-level operating system functions is mostly written in C, while the class library is mostly written in C#.