Another interesting thing I overlooked, Steven Edward Lucco will also be there:

http://gotocon.com/aarhus-2012/speaker/Steve+Lucco

And his presentation is also not disclosed yet, 'JavaScript 5' is not EcmaScript 5, it only means its the 5th presentation in the JavaScript track.

And he doesn't even have a biography. fortunately, someone saved a copy from microsoft.com

Steven E. Lucco is currently the chief architect for the Microsoft Browser Programmability and Tools (BPT) team. BPT builds the Internet Explorer's Chakra Javascript script engine, as well as the Visual Studio tools for creating scalable, efficient Web client applications.

So he is also the JavaScript engine/tooling guy, and formerly a .NET/CLR guy, coincidence ? Perplexed