I've been hearing this a lot lately, and finally started reading up on the roots of the Agile movement. It all goes back to Lean Manufacturing. Oddly enough, I've had exposure to Lean Manufacturing at a previous job. So the concepts and names are all very familiar to me. Back in those days, I had heard of the concept of Lean Software Development, but it never really made any impact on how I wrote software. These days, though, I'm diving into as much Agile as possible and the further down the road that I travel, the more and more parallels I see, to the lean manufacturing world.
If you are at all interested in the roots of agile, here's some recommend reading (mostly Wikipedia) to get you started.
Wikipedia:
Books:
I'm hoping to absorb more of this information, quickly. It seems the more I learn about lean manufacturing, the more I understand about software development. I certainly don't claim to be an expert on either subject... hopefully I can change that.