I think you are more than likely to receive a cease and desist letter from the company's lawyers. I agree with Scott; if you don't have written permission you are asking for trouble.
This sort of thing is not unprecedented. Here is one example involving Blizzard:
[Blizzard have] already sent out cease-and-desist orders to two Warcraft-related iPhone apps that were charging money (Armory Browser and the Warcraft Arena Calculator), and now we've heard from its creator that Warcraft Characters has gotten the C&D treatment as well
Mike Schramm, WoW Insider
This next example isn't specific to an iPhone application, but still relevant. The lawyers at Marvel weren't all too happy when an artist produced something not too dissimilar from what you're describing:
Last February, Michael Mateyko of the design team KOMBOH created the awesome “The Avengers: 50 Years of Earth’s Mightiest Super-Heroes” poster, which features a graphic timeline of Marvel superheroes that spans from 1963 to 2013.
The folks over at Marvel Entertainment saw Mateyko’s poster. Great news, right? Not so much. KOMBOH announced on their website, “Marvel threw a cease-and-desist letter at us and we had to remove all the Avengers and other comic stuff.”
Lauren Kilberg, Paste Magazine