Advantage of .Net 4.0 over .Net3.5 in development side

Hi

 

Can any one give me some advantage of using .net 4.0 over 3.5. I need the answers in development perspective. For Example, I will let u know one thing in .NET 4.0. We can use Tuple in .NET 4.0 but not in 3.5. I guess most of them are familiar with the keyword Tuple. So Please let me know some advantages in development side. 

 

Hope this is clear.

 

Thanks.