It's been a long and grueling process, but it's finally happening.
Here's some background on the series:
Alan Moore, who wanted to transcend the perceptions of the comic book medium as something juvenile, created Watchmen as an attempt to make "a superhero Moby-Dick; something that had that sort of weight, that sort of density." Moore also named William S. Burroughs as one of his "main influences" during the conception of Watchmen and admired Burroughs' use of "repeated symbols that would become laden with meaning" in Burroughs's one and only comic strip, which appeared in the British underground magazine Cyclops.
Moore and Gibbons originally conceived of a story that would take "familiar old-fashioned superheroes into a completely new realm." Initially, Moore looked towards the defunct MLJ Comics line of superheroes for inspiration. "I'd just started thinking about using the MLJ characters — the Archie super-heroes - just because they weren't being published at that time, and for all I knew, they might've been up for grabs. The initial concept would've had the 1960s-'70s rather lame version of the Shield being found dead in the harbor, and then you'd probably have various other characters, including Jack Kirby's Private Strong, being drafted back in, and a murder mystery unfolding. I suppose I was just thinking, "That'd be a good way to start a comic book: have a famous super-hero found dead." As the mystery unraveled, we would be led deeper and deeper into the real heart of this super-hero's world, and show a reality that was very different to the general public image of the super-hero. So, that was the idea."
Dick Giordano, who had worked for Charlton Comics, suggested using a cast of old Charlton characters that had recently been acquired by DC. However, the Charlton heroes were being slowly integrated into the normal DC continuity. Because Moore and Gibbons wanted to do a serious storyline in which some of the newly acquired characters would die and the world would be drastically altered by story's end, using the Charlton heroes was not feasible. Giordano then suggested that Moore and Gibbons simply start from scratch and create their own characters. So while certain characters in Watchmen are loosely based upon the Charlton characters (such as Dr. Manhattan, who was inspired by Captain Atom; Rorschach, who was based upon the Question; and Nite Owl, who was loosely based on the Blue Beetle as well as Batman), Moore decided to create characters that ultimately would only casually resemble their Charlton counterparts.
Originally, Moore and Gibbons had enough plot for only six issues, so they compensated "by interspersing the more plot-driven issues with issues that gave kind of a biographical portrait of one of the main characters." During the process, Gibbons had a great deal of autonomy in developing the visual look of Watchmen and inserted details that Moore admits he did not notice until later, as Watchmen was written to be read and fully understood only after several readings.
And here you'll find lots of info on the struggles the production has faced.
Here's some character stills:
And, the trailer:
The film was directed by Zack Snyder who also brought us 300.