These littlebigbillboards where put up at the end of august. They put up 1000 of them in the cities mentioned above. The theft of and eventual ebaying of was actually endorsed.
Write up dated sept 06, 08
http://littlebigplanetnation.com/2008/09/06/littlebigbillboards/
Only thing now is SackBoy on the ladder
Joystiq posted about a marketing campaign for LittleBigPlanet about a month ago, which involved spreading hidden yard sign-sized LittleBigBillboards around major cities such as L.A., San Fran, and NYC. Now you are saying, these are small as hell. How is Sony going to expect to pick up more sacketeers with such a small and really low budget billboards? Creepingvine was nice enough to grab one and take a few shots of the LittleBIGBillboard. Other than how cool these little suckers are, most of you are OMG October 21st, 2008!! GameStop was right! Let’s just hope these are legit so that your hopes come true! 
BTW, Sony encourages you to steal them!
More pictures after the jump!
If you look to the left of the pole, you can see the little tiny ladder they’ve attached to it; this is my favorite part, because it’s so cute. It looks just like the ladder you see on the “real” billboards. It’s kind of hard to get a feel for just how tiny this billboard actually is in this pic, though, so here’s another one:
You can compare the billboard to the size of my hand holding it up; I’d say it’s about a foot wide, total - maybe a little bigger. In this shot, you can see the tiny fake “lights” they added to it, as well as the walkway - again, just like a real billboard.
The whole thing is made of wood (except for the ladder and the printed part of the billboard), and it feels sort of hand-crafted, which is cool; kinda fits the “hand-crafted” feel of the game, too.
Oh, and the coolest part of the whole thing?
