From AdLand.com: "This smells like a viral campaign to me. Maybe it's even a Washington Mutual ad for checking accounts, since the billboard that that 'p.s. I paid for this billboard using money from OUR joint bank account.' Cute. Or it's for some movie."
Possible. Gawker, however, sussed out a blog for and an unnamed source claiming it's a promo for Court TV.
Whatever the case, the guessing makes the viral awfully catchy.