Note to self (and anyone else with a stubborn, stuck print job).

To get rid of a stuck print job that won't delete:
On the computer hosting the printer (not the client if this is a shared printer), restart the Print Spooler service. That's it!

If you need help with restarting a service:

• Click "Start" or the Windows logo if you're running Windows 7
• Type "services" and press enter
• Find the "Print Spooler" service in the list
• Right-click and select "Restart"
• Close the Services window.
  

This isn't the first time I've had this happen, so hopefully by taking this (public) note, I'll remember. And shoot, maybe it'll help someone else.