This seems a rather rare occurence. Not on all the press certainly, but on this UK poster for Tintin in particular, the name of the writers is the same size as that as the director. And the cast. And the film's subtitle. Indeed, the only thing bigger than the writers' names is the main title of the film – and that it's in 3D.
It helps that it's the school holidays in the UK. And that for many kids used to watching Doctor Who Confidential on a Saturday after their main helping of Doctor Who, Steven Moffat is pretty much the biggest name writer off the television that they've heard of. And if one writer gets that credit, the other credited writing team (note the use of "and" and "&" has to as well.)
A writer having box office cache by name recognition on the poster. Who'd have thought it?