Niner since 2011
@billo:Needed a new version of NuGet. See http://www.wadewegner.com/2011/11/unable-to-find-assembly-references-that-are-compatible-with-the-target-framework-silverlightversionv4-0-profilewindowsphone71/
Also, NuGet was unable to update itself, so had to uninstall the previous version (1.2) and install anew.
@maleny: I have the same problem, with the same setup. Any solution found?
No real content here, but fun to see if you already use ACS. If you haven't used it yet, probably Intriguing to see how easy it is (and it is REALLY easy).