Batman (Bruce Wayne) "died" in the last big DC crossover - "Final Crisis", which tied in to a storyline in Batman's own book, called "Batman: R.I.P." Basically, in "Final Crisis" he was struck by Darkseid's Omega beam, and Superman was then seen carrying his corpse.
Since then, Dick Grayson, the first Robin, aka Nightwing, has been wearing the Batman costume and starring in the Batman books, with Bruce Wayne's son, Damian, as his Robin. The 3rd Robin, Timothy Drake, changed his name to Red Robin and went on a quest to determine if Bruce Wayne somehow survived.
The "Blackest Night" crossover in the Batman/Superman book didn't feature Batman or Superman - it starred Bizarro and Man-Bat instead.
In Blackest Night, the villain Black Hand is seen digging up Bruce Wayne's body, stealing his skull, and recruiting it into the Black Lantern Corps. The skull was briefly reanimated as a Black Lantern, reconstructing a body in the process by Black Hand's lord, Nekron, to move against the Justice League and the Titans. After the Black Lantern Batman created several black power rings to attach to and kill the majority of the Justice League, the skull was returned to normal after Nekron explained it served its purpose as an emotional tether. Nekron also referred to the skull as "Bruce Wayne", implying that he is aware of Batman's current disembodied consciousness as a result of the Omega Sanction.
Advance word from DC says there will be a mini-series where Bruce Wayne will be revealed to be lost in time, and will have to find a way to travel back to modern Gotham City. USA Today has reported that Bruce Wayne will return in 2010 in the six issue miniseries, "Batman: The Return of Bruce Wayne".