Before you get too excited, you can't actually turn your iPad or iPhone's "slide to unlock" feature into a twisting race course. What you see here is actually an interactive ad created by Audi for the iPad, promoting their magazine.
You're still able to actually guide the "slide to unlock" arrow around the course, but upon completion instead of displaying your lap time confirming your unlocking prowess, you're taken to the Audi Magazine in the iTunes App Store.
If you were hoping for a hack or jailbreak trick to replace your iOS device's unlock screen with this, I'm sorry to disappoint you. And while this English version exists, it appears as if the ad, created by AlmapBBDO, was only run in Brazil. So if you don't live there, you may not ever get a chance to try it out. [AlmapBBDO via PSFK]