I just returned from the parks and the only Up pin available was the LE one (bolded in the above post). I checked every pin store/kiosk for the open edition one and no luck. If you are looking for the LE pin, the only places I saw it was at the Contemporary gift shop (Fantasia, I think it is called) and the main pin booth at Epcot.
Edited to add: I found NO Up merchandise in any of the stores at the parks or Downtown Disney. I was extremely disappointed about this as there is tons of stuff for G-Force. I think that Pixar films get little merchandise love, in general. There was way more Wall-E stuff now than there was last year (the same year the movie was released).