In a move by Apple to help curve the way users can accidentally perform an in-app purchase for something they weren't aware of, a new change to the desktop version of itunes warns users the app contains in-app purchases. The new notice appears under the price bar and the app icon in app listings.
This change hasn't made it's way to the app store listings (yet) but my guess is it could be coming soon because that is where the majority of the in-app purchases are being made from.
In the iOS App Store in app purchases are the trending way for developers to earn revenue, but with the mounting restrictions and more 'prompts to purchase', this could become a roadblock for some though I think that if the purchase is a worthy upgrade to the app, then things such as an additional prompt won't matter as much because the user is intending to buy the upgrade and meaning to do so on purpose.