Luhnow has hired away Sig Mejdal to the Astros. See this post for a connection to the book Fantasyland:
I've seen Sig give two talks in the last couple of years (at the Society for Judgment and Decision Making Conference in 2010, and the Institute for Operations Research and Management Science in 2011).
He is a very entertaining speaker. He has great stories about how to mix the sabermetric approach with the old school culture.
His role for the Cardinals seemed to include, among other things, evaluating college players for the draft by creating a systems that would allow the team to compare performances across different colleges/conferences/divisions--essentially adjusting for a "strength of competition" effect akin to ball park effects. He also focused on assessing and blending scouting reports with standard sabermetric models.
Sorry to lose him. The loss of Luhnow and some his staff is the real management story for 2012 and beyond...