It'll be Jason Jennings on April 3rd for the Rockies, facing the Diamondbacks and (one would assume) Brandon Webb. Jennings is maybe the third or fourth best starter Colorado has, depending on whether Byung-Hyun Kim can consolidate his progress from last year, but he does have the biggest salary and arguably has the most to gain from a "vote of confidence" like the Opening Day assignment. You and I know Aaron Cook is the Rockies rotation arm to watch.
Meanwhile, happy birthday to Victor Hugo, Johnny Cash, Buffalo Bill Cody, Michael Bolton, Grover Cleveland Alexander, Marshall Faulk, J.T. Snow, Drew Goddard, and me.