Agile and Lean - complementary or conflicting?

Dave West has contributed an article entitled A Marriage Made in Heaven?. I found it very instructive to read that as well as the comments attached to it. To my mind, there are things that the software community can learn (and has learned) from lean manufacturing, but in many respects software development is much more of a joint creative act. As Dave says, Peter Naur as long ago as 1985 equated programming with collaborative theory-building - in other words, it has much in common with research at the forefront of physics or mathematics, where results are difficult to predict and effort is almost impossible to forecast.