On the same topic, I highly recommend the new book Built to Move that can benefit all of us desk workers.
I do know that a 15-minute "stretch routine" should either substitute or incorporate push-ups, squats, and other, similar basic movements in the routine. Stretching on its own is quite pointless if it's also coupled with continued sitting the entire day and not much other physical activity (walking, weight lifting, running, swimming, sports, w/e).