Unless something changes, I doubt that Congress will ever formally declare war again.
Congress gave Bush about as free a hand as they could in the war on terrorism. A formal declaration of war against, say, Afghanistan would have been too limiting for the diffuse nature of the Islamic terrorists.
I'm going to look up something called Letters of Marque, because they seem to be what this situation calls for. I'll post something here about it when I'm done.
Tuor