I believe Microsoft is planning to keep this as a separate tool, and not include it (at least in the Pro level MSDN subscriptions).
The official thought seems to be Visual Studio->Programmer and Expression->Designer, and officially, the two programs are meant to be used by two separate people. This gives them another revenue source, and a good enough excuse that I doubt they'll change it.
But... I don't work for Microsoft, and I won't pretend to understand the depth's of the craziness associated with Microsoft's development tools business model...