MSR Technical Education Series: Designing .NET Class Libraries
Krzysztof Cwalina (co-author of Framework Design Guidelines) recently did a talk for the Microsoft Research Group on great framework design.
I heard somewhere that .NET Framework started from about 6000 classes in version 1.0 and grew to 18 000 classes in version 3.0. I am not sure how precise are these numbers but they could give rough idea how big is .NET. All these classes should had been carefully designed so watch this video where Krzysztof Cwalina (program manager, .NET Framework Team, Microsoft) esplains how to design such libraries.
The video is more than 3 hours but I am sure it worths.
(via Brad Adams blog)