After I updated my application icon I also made a new document icon. While the application icon shows up fine the documents still have the old icon. Do I need to do anything to help the Finder show my shiny new icons?
Mac OS 10.9, Xojo 2013r4, Cocoa.
Rebuild your desktop database by holding down Option-Command while the computer is booting? 
But seriously - you need to reset your Launch Services database. It’s the modern equivalent of the Desktop Database. You might have to restart the Finder afterwards:
sometimes simply restarting will do.
. or trashing the previous version of your application (the one that have the old icons).