Alcohol was banned in the bleachers long before I ever sat out there so I can't vouch for the craziness, but Sooz can. She has been sitting out there way longer than I have. A few weeks ago they announced that beer will now be allowed in the bleachers and will be sold in the bleachers as well. As if there wasn't enough entertainment out there already. There has always been alcohol out there, just not purchased from Yankee Stadium. According to this article in the New York Post, they will be selling 12 oz. beers for $6. Much more cost efficient to drink a 6 pack from the supermarket in the parking lot for the same amount of money as one beer from them.
The last time I bought a beer in Yankee Stadium was when the Yankees played the Red Sox in the ALCS a few years back because my seats were in the tier above home plate. It cost me $8 for a cup that was warm, or maybe it just seemed warm because it was about 30 degrees out. I took 2 sips and handed it to my brother who was happy to have it.
I can bet that on Friday or Saturday I won't be purchasing a beer despite the "coolness" of finally being able to after years of sitting out there.