tapulous-jennifers-body-screenshotTapulous, maker of the popular Tap Tap Revenge game for the iPhone and iPod touch, is launching a contest today to promote “Jennifer’s Body,” a new film from 20th Century Fox. This is far from the first time movies have been promoted in iPhone apps — in fact, Tapulous ran a previous promotion for “G.I. Joe” — but the Palo Alto, Calif. company says this is the first contest based on user-generated material. (I’m not sure I agree, but I’ll get to that.)

Taken by itself, the fact that movie studios are now coming to Tapulous to pitch campaigns is yet another sign that the iPhone is maturing as an advertising platform.

In Tap Tap Revenge, players tap different parts of their screens in rhythm as a song plays; Tapulous has struck deals with record companies like Universal Music Group to feature different songs and musicians in the game’s backgrounds. For the new contest, players create a Jennifer’s Body-themed background to go with the Panic! At the Disco song “New Perspective,” which is featured on the movie’s soundtrack. You can either pick-and-choose from different background elements provided by Tapulous or build your own theme in Photoshop. Either way, I’m going to go out on a limb here and guess that the winning theme will feature Jennifer’s Body star Megan Fox being sexy.

The contest will run until Sept. 7, then the winner will be selected through user voting; the winning entry will be featured in the game, which the company says has already been downloaded more than 11 million times. (There are several other prizes, too.)

I’m not entirely convinced by Tapulous’ claim that it’s holding the first user-generated contest — you could argue it was beaten to the punch by Smule’s “This Contest Blows,” where users shared and voted on musical recordings made using the Ocarina app. I guess the difference is that Tapulous’ contest winner will actually be included in a game with existing, professionally-built content.

Tapulous has raised almost $3 million from investors including Andy Bechtolsheim, Marc Benioff, Rajeev Motwani, Katrina Garnett, Rob Theis and Jeff Clavier.