I'm the development lead on ASP.NET MVC at Microsoft.
There are no plans to include multi-project areas in ASP.NET MVC 3. However, it's definitely an area that we plan to revisit in the future.
In the meantime MvcContrib's solutions are probably the best bet. The MVC Futures download still includes an old (and perhaps only semi-functional) version of the original multi-project areas feature. Because the full source code for it is also available, you might be able to construct a solution that is customized to your needs.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…