Years ago Microsoft published large parts of the .NET-Framework for debugging purposes. There were many problems with that approach. The biggest issue was the required configuration combined with the lack of knowledge that something like this even existed.
Now we finally have a very lightweight approach to that problem. If we are really interested how something is implemented (e.g. if List<T> in .NET is like a vector<T> or a list<T> in the STL - well, the answer should have been obvious since there is a property called Capacity) then we can just have a look.
There are some interesting parts (especially stuff that is commented out), some obvious parts and some frustrating parts. All in all some areas of .NET will loose its magic for sure. But that is a good thing, since in the end this will lead to more innovation and probably one or the other bug-fix.
To make this tool even more helpful Microsoft also released a VS extension that can jump to the correct place on the webpage from Visual Studio. Together this seems like a must-have.
Thanks to the whole .NET team for making this happen!