On Wednesday I picked up a brand new Incase slider case for my iPhone. But it wasn’t a physical case, it was a Gowalla item — the first such branded Gowalla item I’ve picked up. I’ve heard of these, and I know Foursquare has branded badges you can unlock for checking into certain venues, but how much do these cost? Are they giving them away right now to build buzz? Do these companies even have sale forces? And how do you measure how effective these badges are?