If it was built after Aug 1st, it definitely has it. If it was built before that, it might have it if it was one of the vehicles that got updated before shipping from the plant or if it was on the dealer lot, they may have updated it too.
There's a sticker on the side of the driver's door when you open it. If it says 0807 for the build date, you're all set. If not, then I think you can go somewhere and type in your VIN and it will tell you the build date. I think I saw a thread on the Acadia forum with the website. If it was built before Aug 1st, but you bought it off the lot mid Aug, then the dealer may have updated it. You'd have to ask them.