You know those hardcore fans who go to certain movies just to see a trailer for an upcoming movie they're excited for? It's not a common sentiment, but it happens more of then than you'd think. I wonder if those fans would do the same thing for a poster.
According to MTV, Jerry Bruckheimer had a number of posters for his upcoming films inserted into Confessions of a Shopaholic, as Times Square billboards in a scene halfway into the movie. One of them is the poster for Mike Newell's Prince of Persia: The Sands of Time, the first time we'll see any artwork from the film.
I Am Legend featured a similar easter egg, with movie posters scattered throughout the film's Times Square scene; but the ones featured there were posters for fictional upcoming movies like Batman vs Superman. These ones are real. In addition to Prince of Persia, Shopaholic audiences will also get to see a poster for Bruckheimer's guinea pig family film G-Force, though unfortunately for them, it's a poster for G-Force.
Prince of Persia: The Sands of Time, of course, is the Pirates of the Caribbean-esque movie adaptation of the popular video game franchise of the same name, starring Jake Gyllenhaal as the Prince. Confessions of a Shopaholic, on the other hand, is the story of a woman who moves to Manhattan to become a financial advice columnist and nurture her shopping addiction at the same time. Not to worry, though, because she then falls in love with a handsome rich entrepreneur.
(Thank you, but no. If Isla Fisher's character doesn't end up broke and homeless with no savings after losing her job at the end of the film as a result of her shopping addiction, then this movie has no business playing during a recession. Who knows, maybe she does?)
If you are as perplexed as I was when I heard this as to where the audiences for these films overlap, give it another thought. Maybe Jerry B. got it right. Maybe the poster is more eyecandy for Shopaholic's female audience than the gamers, since it likely features a buff and shirtless Jake Gyllenhaal attempting to look Persian.

Exhibit A
Wait... Or is it Iranian now? I always get the specificity of the distinction confused. It should be Iranian, though, because as SNL pointed out, Jake Gyllenhaal could pass for one.

Exhibit B
Data is inconclusive as to whether or not the American public would flock to a summer blockbuster called Prince of Iran.