You can make a overnight or 2 day shipment stand out on your order list page. Here's how:
Go to your Shipping methods/Conditions area and edit the method that you wish to have a notice show for. Check the box labeled "Highlight Orders with This Shipping Method". Then Save.

You will now see a notice icon on your order list page letting you know of all orders that use this particular Shipping method. You can apply this setting to as many urgent shipping methods as you like.
