[_delirium]

AGPL's a version of the GPL that considers "running a modified version as a webapp" equivalent to what counts as "distribution" with the normal GPL. The goal is that if, say, Amazon AGPL'd their EC2 infrastructure, and you created an improved version that you then put online as your own cloud provider, you'd have to release your improvements. The normal GPL wouldn't require that, because running a service off code isn't considered "distribution" of the code (the code itself never leaves your servers). People who use the AGPL, though, want semantics roughly equivalent to what the GPL got you with fat-client apps: if someone made and sold a modified version of your GPL'd offline word processor, for example, they'd have to GPL the modifications.

Not sure it makes any difference with .js code, though, because in that case the code is being distributed, so the normal GPL would already apply.