I'm confused with the comments here - we do all know Garageband is the app in the ad, right? It just so happens that people see a piano and search "piano" in the app store.
Yes, GarageBand is the app in the commercial. Why would Apple feature someone else's piano? :-) But it is nice that they said "App from App Store" instead of being more specific. That allowed the rest of us piano app developers to benefit.
p.s. I hope I'm not the only one around here who thinks of Tom Hanks when I hear that tune. I suppose all the kids downloading my app don't think of "big" when they see the TV ad.
I may also be missing jokes and/or sarcasm :)