C# 3.0 introduces implicitly typed local variables. You do not need to specify a type for a local variable any more! The compiler figures out which type to use for you. So what do you think; does the following code work?
namespace ImplicitTypes
{
    class Program
    {
        static void Main()
        {
            var v = "Hello World!";
            v = 10;
            System.Console.WriteLine(v);
        }
    }
}