This is the official Microsoft newsgroup for Managed DirectX - sometimes Tom Miller or other members of the DirectX team show up.
microsoft.public.win32.programmer.directx.managed (Google Groups)

This is the official DirectX graphics newsgroup - useful for the really technical stuff.
microsoft.public.win32.programmer.directx.graphics (Google Groups)

There is also a specific newsgroup for programming DirectX from Visual Basic.
microsoft.public.vb.directx (Google Groups)