C# 5.0 adds asynchronous methods [1] and caller info attributes [2] to the language. They also changed respectively fixed the way foreach loop variables are captured in closures [3] and changed the overload resolution algorithm [3] and argument evaluation order [3].

[1] http://msdn.microsoft.com/library/hh191443.aspx

[2] http://msdn.microsoft.com/library/hh534540.aspx

[3] http://msdn.microsoft.com/library/hh678682.aspx

I'm sorry, I meant that I didn't see any differences from the C# 5.0 specification released in August 2012 and the revision posted here, which was updated in June 2013. I am aware of the differences from c#4 to c#5.

My point being that c# 5.0 is around 1 year old, and this spec is not new.

Maybe someone else will still find the information helpful. I also just noticed that the copyright still says 1999-2012 - maybe they just reuploaded it.