Personally, this is exciting news for me as a Silent Hill fan. The third game had one of the best stories in the series to date. It was a follow up to the original Silent Hill, in which players too control of a teenage girl named Heather, who was eventually revealed to be the daughter of the first game's protagonist, Harry Mason. Here's the official synopsis from Fangoria:
"For years, Heather Mason and her father have been on the run, always one step ahead of dangerous forces that she doesn't fully understand," reads the official synopsis. "Now on the eve of her 18th birthday, plagued by terrifying nightmares and the disappearance of her father, Heather discovers she's not who she thinks she is. The revelation leads her deeper into a demonic world that threatens to trap her in Silent Hill forever."
Of course, the 2006 Silent Hill film has no relation to the sequel, apart from the haunted town te stories are set in. For more details, visit the source articles over at Fangoria and Kotaku.
Silent Hill: Revelations has no release date given yet. Check back from time to time for more updates as they come.