I am pretty sure it is. Can't think of any reason it wouldn't be. Could double check the Minneapolis Park & Recreation Board website to be sure. Assuming, you have been there before though you probably already know all the in's and out's of it.
Last year the only hiccup that our group noticed is that the "daily rate" parking is still in play, so actual spots on pavement were limited or full depending on when you showed up. The parking attendants showed up around 2:00 IIRC. Our group got there bright and early and paid the daily rate, which I think the attendants honored. No issues with tailgating right away were had. As with any lot, it's always best to make an attempt to communicate and follow the rules, so you get recognized as one of the "good groups."