While the June CTP (or Beta 1 refresh if you will) of Visual Studio 2008 is already out some time, I didn’t see anyone report on a new feature that was introduced: “Organize Usings”
When you right-click any code file, you get the usual context menu, now with an extra menu item:
It does exactly what it says: remove any imports of namespaces that are not used in a particular code file and/or sort these alphabetically. You need to perform this action against every code file individually.
This will come in handy.