Great trick, easy to perform. If your card handling is OK, then learning this will be very quick. Now at first you'll be underwhelmed at what you receive, but go out and work this for some real reactions. There are two methods presented:
1) Spectator 1 chooses and signs a card, spec 2 simply memorizes another. You reveal spec 1's card has moved to the top, and spec 2 is now holding their card instead of the sharpie.
Version 1 is great for walk-around or table hopping and requires a 5 second reset. The pocket space required is minimal (an extra sharpie) and is an excellent card reveal. Of course if you've done the "memorize your card" bit before, you realize that all spectators forget their card within 30 seconds. So be sure to have them show it around to friends. You receive two special cards but get a PDF on the DVD to print more. NOTE: Use the full sheet sticker paper instead of trying to align up the template with whatever is offered at your local office supply.
How long the cards last depends upon how violent your spectators are with them. But with regular handling should last a good 3 months per card of regular use.
2) A single spectator chooses and signs a card, which transforms into the sharpie.
Version 2 requires you to print out special card stickers and affix them to the deck of your choice. You cannot use the included 2 special cards for signatures, since once those are gone, you gotta buy expensive refills. Alakazam said they were trying to get a full run printed so we can buy a whole deck of these, but until then you're stuck with the print solution. This requires some beginner card work to pull off, but still not all that difficult.
This is obviously the stronger version, as you can tell from the brunette in the demo rambling on about "best stuff evah". Version 1 gets a "wha?" kinda confused reaction, while v2 leaves them speechless.
Whichever method you choose, you will probably be happy with this very commercial effect.