Yeah, I tried Jeff's (trpnbils) 10% method and it came out within an inch of the actual length determined via Serp's program. The only thing to keep in mind when using Serp's program is you gotta keep the camera almost perfectly level with the surface the snake is on, otherwise the pic is slightly skewed and thus the measurements are too. That program is great though - saves tons of time when trying to measure a wiggly snake!
Edit: My 24 inch snake's last shed was 2 inches longer than she actually was, just to put things in perspective.