I recently went to a BCS SIGIST Conference in London and was quite frankly shocked by the number of QA Professionals that weren't working in an Agile environment. In my past, I have worked in a Development Team that ran with the Waterfall approach, but in recent Years (whether I've realised it or not), I've been working in Agile Development.
More recently, my company 'Immediacy' (or Alterian as we're now known) has been using SCRUM, which is a Lightweight Management Framework that makes it really easy to demonstrate the progress of the project to both you and your customer. I certainly couldn't go back to the archaic practices of Waterfall, or 'dumping over the fence' as I've often been known to refer it to.
My boss sent me this useful Google Video recently, which is a really good insight into Testing in an Agile environment. Give it a watch.........it's really interesting.
Agile Testing Video