If you're interested in attending, the turnstiles between Gates 4 and 6 will be open at 3:30pm for the 4:13pm start time. Admission appears to be free, but there will be plenty of opportunities for you to blow through some benjamins as the food and concession stands will be open. NYY Steak and the Hard Rock Cafe will also be open.
If you can finagle your weekday schedule to make this work, it's a great way to get to see the new stadium without taking out a 2nd mortgage on your house. Those community-loving Yankees are so charitable, right?
More info here.