title: Which new C#/VB features require .net Framework 4?
body: <p>I remember reading in passing that some of the new language features in C# and VB that are available in VS2010 are backwards compatible with earlier versions of the framework, but that others are not.  I'm pretty sure this was in reference to the new property syntax in VB.</p>
  
  <p>Which new features are language features vs which ones are framework specific?</p>