Apparently no. See this article at Ars technica (http://arstechnica.com/microsoft/news/2011/06/windows-8-for-software-developers-the-longhorn-dream-reborn.ars)
Basically the new HTML5 & Java front-end is one layer and .Net etc. is being kept but mor eclosely integrated with a new API replacing Win32, giving C++ code direct access to WPF and other stuff limited to C#/VB until now..
I'll believe it when it ships. They have a habit of mentioning all these cool new features, and then cutting them before launch...