Channel 9 have just published a great video with Mads Torgersen. In it he covers some of the features of C# 6, mentioning the new FormattableString class to which an interpolated string expression can be cast to in order to access additional functionality. Most of the video is about some potential C# 7 features, which include pattern matching and valuetype tuples whose type includes the name of the item in the tuple. There will be work on improving the performance of structs by allowing the return of structures by reference. There is also talk of more research into reference types that do not include the null value. Torgersen also touches on the expression problem when discussing the emphasis on including more functional features into the language.
On a related.NET note, there’s this recording of David Fowler talking about the internals of the new ASP.NET. He follows a request as it makes it way through the new platform, including a dive into the internals of the new Kestrel web server, which uses libuv to allow the same code to work on Windows and Linux. The leastprivilege blog had a recent post that looks at authorisation in this new framework.