The LA Times ran a story a while ago discussing the man in charge of the snakes in the movie, Jules Sylvester:

For “Snakes on a Plane,” which stars Samuel L. Jackson as an FBI agent escorting a witness on a flight from Hawaii to Los Angeles when assassins release hundreds of deadly snakes, Sylvester drove some 450 snakes from Los Angeles to the Vancouver location — “I think there were 27 different species of snakes,” he says.

But only 60 were used at one time. “You have very controlled areas [on the plane] where you were shooting,” says Sylvester. “We mixed it with computer graphics and animatronic snakes.”

Here’s his webpage.