Holy Hell, Ringo, where have you been? It was released on DVD back in October of 2005. There was a discussion on it in the Mclintock movie review thread as where as elsewhere on the site, I'm sure. At any rate it's a great, full restored and remastered DVD in widescreen with perfect, crystal clear picture quality, and a whole bunch of extras. A must for any Duke fan's collection.
Cover shot (make sure you buy the DVD that looks like this one, the others are the cheap, public domain knockoffs):
You can buy it online here: