SharePoint Foundation 2010 Objects with .NET 4

You Cannot Use SharePoint Foundation 2010 Objects with .NET4 

The SharePoint Foundation 2010 object model is not accessible using the .NET Framework 4 (or
later).  Calling any object or method in the object model using any framework version other than .NET 3.5 will throw the following exception: 

System.PlatformNotSupportedException

Microsoft SharePoint is not supported with version 4.0.30319.1 of the Microsoft .Net Runtime.