Conventional wisdom says that any manager of people who can do the work they're asking others to do has a leg up on a manager who can't. Do you buy that?
All things being equal, I think it's true. If a manager can be active in the type of work going on in his shop to show that he or she is a subject matter expert, I think it's going to allow them to be a more effective coach.
Case in point - Shaka Smart, the 33-year old basketball coach at VCU. VCU had an improbable run to the Final Four this year, and the video clip below is from their public Final Four practice. The drill is the "Ironman", where each player has to take a charge, dive for a loose ball and then run/jump to save a ball going out of bounds. It's a drill used to encourage players to provide more hustle, which in the workplace could be called "discretionary effort". Which is what you want lots of...
Here's the twist. To pump up the players, Smart did the drill for the players. Before the cynic in you comes out with the blades, watch the video and observe the players following Smart around the court as he performs the work. What you observe could easily be catagorized as "engagement".
Doing the work you ask others to do. Not all leaders are in the position to do it, but when you can, it's certainly an effective leadership tool.