WubbiConcepts | Minecraft: Glitchy elevator @WubbiConcepts | Uploaded 12 years ago | Updated 19 hours ago
This is based on a piston glitch in 12w26. It creates phantom pistons which have the collisionbox and texture of pistons, but don't really exist. As soon as you update them (right click) or you reload/rejoin (yes, this works both in SSP and SMP) they just disappear.
I'm pretty sure this will get fixed before 1.3 comes out (that's why i don't show you how to create them).