We've gone beyond voluntary licensing of parodies: Some companies are now paying to be mocked, as a variant of product placement. Being parodied proves your brand is valuable.
I've written about the empirical failure of the argument that IP owners won't license parodies. This new twist takes trademark law into an even deeper conundrum. If consumers are well-educated about product placement, as evidence suggests they increasingly are (Henry Jenkins's new book Convergence Culture discusses this in the American Idol chapter, as does James Gibson's piece, coming soon to a major law review near you), then they may well assume that even the unflattering uses of a product are authorized. But turning that into an infringement case is a really, really bad idea, for the free speech/pro-competition reasons we all know.
Developments of this sort increase the pressure on courts to create rules, like the nominative fair use doctrine, that essentially declare that whatever the de facto confusion, there is no de jure confusion -- no confusion the law will intervene to stop. I borrowed the de facto/de jure terminology from functionality doctrine, but it explains some otherwise mysterious things about nominative fair use and related trademark doctrines.
The new focus on "use as a mark" as an element of infringement, paralleling the "commercial use in commerce" as an element of dilution, is a related way for courts to avoid inquiries into actual confusion. Finding that a product parodied in a TV show isn't being "used as a mark" is a much cheaper and cleaner way to allow the parody than reliance on the multifactor confusion test. The latter allows the trademark owner to introduce evidence that some consumers actually believed that Caterpillar endorsed George of the Jungle 2 or that Slip 'n Slide was associated with Dickie Roberts, Former Child Star. Essentially, we can no longer rely on consumer perceptions to define the appropriate scope of the "endorsement, association, or affiliation" branches of infringement law -- if we ever could.