Visual Studio can help migrate your Outlook solutions from .NET Framework 3.5 to the .NET Framework 4. However, you still have to do a few things manually to make it all work. 

Beth Massi converts an Outlook Solution that targets the .NET Framework 3.5 to an Outlook Solution that targets the .NET Framework 4 client profile in this very cool and informative blog entry - Migrating an Outlook Client to .NET Framework 4 in Visual Studio 2010.