Red band trailers? Who knew?

The Los Angeles Times has an article about the new phenomenon of 'red band' trailers for movies, where it includes "unrestricted content, meaning all the gore, drug references, bare breasts or foul language that have to be edited out of the typical trailers shown in theaters or cut down for thirty-second television spots".
The article links to one at Slate by Josh Levin on the same subject:

As you'd expect, the trailer for Kevin Smith's Zack and Miri Make a Porno explains the movie's premise: Zack (Seth Rogen) and Miri (Elizabeth Banks) become adult-movie stars when they can't pay the rent. What you might not anticipate is the trailer's extreme lewdness: Justin Long name-checking a gay porn film called Glen and Garry Suck Ross' Meaty Cock or Rogen's declaration that he'd be happy to watch "a tape of Rosie O'Donnell getting fucking stupid." Vivid descriptions of male genitalia and Rosie O'Donnell in flagrante delicto— these are the glories of the red-band trailer.
According to the Motion Picture Association of America, nearly 30 restricted-audience trailers have been approved so far in 2008, already matching the number accepted between 2000 and 2006. (All-audiences movie trailers, always prefaced by a green band, still run before the vast majority of cinematic fare.)
The MPAA places more restrictions on what you can and can't see in trailers than it does on the content of feature films. Restricted trailers may not show "excessive sex or violence," "dismemberment or excessive gore," or "genitalia/pubic hair," among other things. All-audiences trailers are governed by an even more draconian code, leading to such salami-hiding absurdities as a weed-movie advertisement that doesn't mention weed. Along with the ban on drug references, green bands can't include "ménage à trois, group sex or nudity of any kind … scenes containing blood or open wounds … [or] offensive language, gestures or lyrics."
Red-band trailers weren't particularly common before 2000. Just as an NC-17 rating branded a feature as outré, restricted trailers in those days were mostly reserved for scandalous material like Showgirls and Madonna's Truth or Dare. Universal's R-rated preview for 1999's American Pie, for example, highlighted the film's man-on-crust sex scene, making it clear to audiences that this was a different kind of teen comedy.