Looks more like a Euphorbia than a "true" cactus. With a bit of time you should be able to find it on this page: http://www.desert-tropicals.com/Plants/Euphorbiaceae/Euphorbia.html
Thanks for the link! I looked at all their Euphorbias and nothing comes close. When I first saw it I thought it was a Euphorbia but the closest thing to it I could find was a kind of Cereus Monstrous. Thanks again...I'll keep looking!
Thanks TonyR... I think you nailed it! I found a pic of an identical one on-line. They are beautiful!
tony beat me to it, nice specimine. love the columnar monstroses, ive got a trichocereus bridgesii monstrose colum, not the clumping type :)