Anand [MS - Sandacastle team] has just let us know that VS 2010 Beta 1 will be Online Help only (in the browser).

The offline (local help) experience wont be available until Beta 2. The current plan now is to also view offline help in the browser.  Originally they were thinking of a C# application with WPF UI.

Hopefully Beta 2 is when we can start integrating. So relax for a little while longer.