I assume those are Airpush advertisements. Some applications come with them, and you get the notification popups, seems to be quite annoying.
https://market.android.com/details?id=com.brosmike.airpushdetector <-- something like that may be able to give you a clue as to what is the offending app. If it is indeed airpush that is. There are airpush blockers on the market as well, I am not too sure how well these work though as I have never had an airpush ad.
I delete any app that pushes those. I don't care what the app is, it's gone.
I'd honestly rather they be in my notification bar, than cluttering the interface of the app. Especially evident in fast action games, those in-app ads always cause a framerate hiccup when they change.