title: VS2008 can't reference a .NET 3.5 assembly built in VS2010?
body: <p>I know that VS2008 can't work with .NET 4.0 and that the .NET 4.0 assembly file format has changed from 3.5. However, I would have thought that assemblies built by VS2010 targeting .NET 3.5 or earlier would be compatible with VS2008.</p>
  
  <p>Attempting to reference a VS2010 DLL results in the yellow caution overlay on the icon, and a "This project cannot be viewed in the object browser because it is unavailable or not yet built.  Please ensure that the project is available and built." dialog pops up when you attempt to open the reference.</p>
  
  <p>The VS2010 assembly is being built as Release/Any CPU - and this is on Windows 7 32-bit. The assembly is not being signed.</p>
  
  <p>What am I missing?</p>