Here is the MPAA's latest. This was pointed out by The Onion's AV Club (both images taken from that page - "The MPAA Hates Kevin Smith")...
Amelie Gilette at The AV Club comes to the quite funny conclusion that...
"The MPAA hates sexual imagery, unless it involves Dane Cook. "Fully clothed and quite innocently looking people with tufts of hair: bad. Dane Cook, completely nekkid, smug and cocky smile with a blonde head of hair at his groin: okay.
The AV Club pointed out that they're not sure if the Dane Cook one (or the Jessica Alba one with her clutching a phallic, dripping ice-cream cone) were approved by the MPAA or if they were just part of an internet campaign, but the Dane Cook one does turn up on the IMDB page for the movie - does this mean anything?
After watching Kirby Dick's This Film Is Not Yet Rated - a hilarious and scathing documentary about the MPAA - a part of me is suspicious that it's the image of Elizabeth Banks getting head and that big happy grin on her face. In fact, not even the grin - it's clearly a ridiculous, non-in-the-throes-of-ecstacy grin - I think it's just the cunnilingus they're uncomfortable with. It seems - from the evidence in that doco - that seeing women being pleasured sexually freaks them out a lot more than men.
I also recommend this short but funny article posted there too about censoring/revising Watchmen E.T.-re-released style ("The MPAA Thinks You're Stupid").