The idea that the source for any code should have some sort of license attached to it - rather than relying on whatever the local laws are - is a good idea. In code, implicit is elegant. In legal, implicit sucks. I'd like it to be clear what I can/can't do with code I find posted somewhere.
Another, much less flexible, option - the one used by the Linux kernel developers, apparently - is to have a blanket license on the Code Catacombs area that covers any code posted therein, and any poster has to click 'Accept' before the code is posted. Simpler, but reads 7 on the Policy Evil-o-Meter. :-)