That surely was an impressive presentation, but I also have some questions:
Refering to the example he brought with the Method WriteBag(), I'm wondering what would have happened if he wrote AvgPrice instead of Price.
Calling the method with the dynamic type - for my opinion - woul have thrown some kind of "IndexOutOfRange" exception because this Property was not in the bag.
Calling it with the var, I guess would throw a "MissingMemberException".
Without any intellisense I'm wondering how you really would write code in the way he showed that office example. I guess I don't even know all my methods of the code I have ever written, so I might really be unable to just go on and type: > myObject.SomeMethod(withTheRightArguments)
without any IntelliSense. I might not know what I'm actually calling there. So I guess developers would write code with static typing and then refactor it to dynamic? No they won't.
The compiler as Service is quite nice, but I guess you can find about hundrets of Scripting-Hosts written in C# doing in memory compile and further more. I for my self have just do this by calling one of my classes: Active.DynamicClassCompiler.Compile(string code) and I could go on with the compiled class ...