I may not have the story completely right, but the gist of it is that elf has magic powers and the kids can't touch the elf or it will lose its power. The elf was sent by Santa to monitor the kid's behavior and flys back to the North Pole each night to report to Santa. Each day the elf returns, but since elves like to play games, he may hide and appear in a new location. On Christmas Eve, the elf retires back to the North Pole and waits to rejoin the family for the next Christmas Season. You can read the full "Elf on the Shelf" story here.
Anyway, my co-worker has shared stories of her kids' excitement over the elf and how much fun it has become. Some of my favorites that I've seen on Pinterest and Facebook are here:
Did you catch that? Not only can you buy a boy or girl elf, but you also have the choice of a "light" or "dark" elf! Shut the front door! You mean I can get my future kid an elf that has his (or her) skin tone?! I was sold! (Oh, and not to mention that I got 20% off with my educator's discount! Woot! Woot!) Now, I just had to decide on a "dark boy" or a "dark girl" elf.
Linking up...go check it out!