Back in one of my college film classes the professor, a noted expert on the period known as "Pre-Code Hollywood," brushed off a silly description someone had given of some forgotten B-movie by stating that "inter-species sexuality is something that the Hollywood Production Code probably would've frowned on."
Upon hearing this I immediately thought of the 1985 film "The Muppets Take Manhattan"- yes, it ends with an historic frog-pig wedding (likely the first and only in motion-picture history), but what really struck me was the subplot involving the endearing but ultimately unconsummated flirtation between Kermit the Frog and "Jenny" (a human female), and Miss Piggy's bitterness and jealousy over the matter. While of course the Hollywood Production Code was long gone by the '80s, I can understand why Henson & Co. would be skittish about human-frog intercourse - though why is it considered acceptable for Kermit and Miss Piggy (who are of two species just as different from one another as frogs and humans) to not only romance each other for decades, but eventually join in holy matrimony?
Fast forward to 2002. The sex-between-humans-and-talking-animal-puppets taboo has been shattered numerous times on television and in movies, most notably on the now-canceled series "Greg the Bunny" and in numerous bits involving Triumph the Insult Comic Dog (just tonight, Triumph was seen in a music video violating J.C. Chasez of 'N Sync).
There's even something called the "furry" movement that's starting to creep out of fetish circles and into the mainstream (at least, among those who read Savage Love.) I'd like to think, though, that even after Jim Henson's death we can still count on the Muppets to maintain their innocence, and not go off screwing around with people. But I guess I counted wrong because now even the Muppets have been corrupted.