Some people asked me about obsfucation and IP protection.
Myself is strongly against obsfucation. And I believe as a platform vendor, it is critical that we ship our framework without obsfucation.
Fortunately, most people do agree with me. And we do ship .Net framework not obsfucated.
But I do understand why you need obsfucation.
This MSDN page discusses .Net obsfucation. It uses Dotfuscator by PreEmptive Solutions as an example. But the concept can be applied to other obsfucators.
If you want to find a commercial obsfucator, google and you will find some.