I have never worked in an 'agile' environment, so take what I say with a grain of salt. We did, however, cover agile methodologies in grad school. From my understanding, agile is a way of developing software. And although there are technologies and frameworks that naturally lend themselves to agile methodologies, they are not necessarily a requirement, nor does using them automatically mean you're doing agile development.

Actually, the Wikipedia article looks quite good. It's long, but probably does a better job explaining than I could.