I heard about this on a DotNetRocks podcast the other day, it seems the site is live now. From the site:
Developers can target either web browsers or the CLR as clients and Volta handles the complexities of tier-splitting for you. Volta comprises tools such as end-to-end profiling to make architectural refactoring and optimization simple and quick. In effect, Volta offers a best-effort experience in multiple environments without any changes to the application."
Check it out here: http://labs.live.com/volta/