Now that Beta 1 has shipped I am finally allowed to talk about the new/changed security features in 4.0 – but there is no one who can explain these things more elaborate and insightful than Shawn. I just saw that he is about to start a series of posts on the new feature areas. So watch his space closely!
(ah – and btw – leave a comment on his blog that he should write a book about security in .NET 4.0 – maybe we can convince him ;)