I missed this at the time, but TBS just showed replays, and Posey was very clearly out. He was ruled safe, though, and the Giants went on to score what still stands as the only run of the game.
In the Rays vs. Rangers game, Michael Young homered after the umpires ruled he checked his swing. In the Twins vs. Yankees game, Lance Berkman doubled after the umpire ruled a pitch on the corner a ball. And here, we have this. Umpires just can't help but end up as the story.