There's been a lot of noise from DC Comics and their parent company Warner Brothers ever since Marvel became their own studio and hit a box office home run with Iron Man. Let's separate rumor from reality and break down what's actually happening at the studio...

Definitely Happening

Green Lantern - Starts shooting in 2010 from director Martin Campbell (Casino Royale) with Ryan Reynolds as the cosmic ring-bearer Hal Jordan.

Jonah Hex - Josh Brolin stars as the title character in this horror/western from director Jimmy Heyward, set for wide release June 2010.

Lobo - This is slated to be Guy Ritchie's next film, hot off of Sherlock Holmes. The movie will be a PG-13 action-comedy, which has some of the more bloodthirsty Lobo purists in a tizzy.

Batman - While no formal announcement has been made about a new Batman sequel (allowing internet rumor mongering and fan speculation to run wild), this movie will happen, just as sure as there's a setting sun.
Probably Happening

Shazam - It's probably not happening with screenwriter John August, but they're still looking for an angle on the character and, as far as I know, Peter Segal is still the director attached, if the project doesn't stall out completely.

Swamp Thing - Producer Joel Silver made the announcement in August 2009 that he wants to revive the property in a new 3-D movie.

Teen Titans - First announced in 2007 with producer Akiva Goldsman and screenwriter Mark Verheiden. Originally slated for a 2011 release, that date doesn't seem realistic unless the project picks up steam again.

Hawkman - Pajiba.com reported yesterday that Warner Brothers was trying an approach that combined the high adventure of an Indiana Jones film with the star-crossed lovers romance of Ghost.

Preacher - As far as I know, this is still on Sam Mendes' plate, from a script by John August. That seems like a better creative fit than the director originally attached, Mark Steven Johnson (Ghost Rider, Daredevil).

Deadman - In 2006, Warners announced that Deadman would be getting the big screen treatment from producer Gullermo Del Toro. Del Toro has mentioned the project sporadically over the years, so it's obviously something he's still hoping to get off the ground.

Super Max (aka Justin Marks' Green Arrow movie) - At one time the studio was really up on this script (which pitted Green Arrow against a variety of super-villains in a maximum security prison). David Goyer worked on a re-write, and seems to believe that the movie will still happen soon.

Plastic Man - Plastic Man has been in development hell for years now (I seem to remember Bruce Willis being talked about for the role back in the early-90's). Most recently, The Wachowski's were circling the film, but the lack of success for Speed Racer seems to have delayed their progress on another kid-friendly property. Warners seems committed to a Plastic Man film, though, so I guess it's only a matter of time.

Suicide Squad - Announced earlier this year, the super-villain team film is being set-up with producer Dan Lin (Sherlock Holmes) and screenwriter Justin Marks (Street Fighter: The Legend of Chun-Li). I think the "villains forced into a special ops team to win their freedom" concept is gold.

Not Happening Anytime Soon

Superman - Superman is currently dead in the water. It seems likely that Warner Brothers will dust off the character again someday (even if it requires legal wrangling with the Siegel estate), but for right now, they're focusing on their lesser known heroes.

Wonder Woman - This project seemed to stall out (and lost fan support) when producer Joel Silver rejected Joss Whedon's take on the Amazon warrior.

The Flash - This is the DC character everyone thought Ryan Reynolds would play, before he took the Green Lantern role. David Goyer was previously attached as both writer and director on this project, but I don't expect to see any movement on The Flash again until after Green Lantern is released.

Supergirl - Taylor Swift was named by anonymous sources as the number one pick to play the role. Please, nobody break it to Swift that there's no Supergirl movie actually in production. It'd break her heart.

Justice League - A couple of years ago, this was looking more and more like a reality, but it all fell apart somehow. Director George Miller has returned to the Mad Max series, and the project is DOA. This project will probably be revived if Warners decides they'd like their own version of Marvel's planned Avengers flick.

Constantine II - The movie developed a sizeable cult following, and Keanu Reeves would like to have another go at the character, but the more time that passes from the original's release, the less likely a sequel seems. My suggestion? Throw John Constantine into that planned Swamp Thing film where he belongs (the character made his debut in that comic).