I don’t know how new this is. After I registered for Fall 2016 Double Up, I noticed ‘View Promotions’ at the top of Hilton.com.
It goes to Promo Central. The page appears designed to list registered and eligible promotions. It does not appear to have a promo tracker similar to other hotel chains.
My Promo Central does not yet show my Double Up registration. The Get the Hilton HHonors App link goes to a Double Up page rather than something about the app. Seems Promo Central is not ready for prime time.