The official Stephen King website has just received a facelift and also includes additional information on upcoming projects. A new short story, titled Under the Weather will be available with paperback editions and an updated e-book edition of Full Dark, No Stars:
"Stephen's new short story, 'Under the Weather' (written just in the past month or two) will be included in the U.S. paperback edition and as a new e-book edition of Full Dark, No Stars which will be released on May 24, 2011. It will be in Hodder's ebook edition releasing on May 24th and their mass-market edition which will be released at the end of July."
There isn't any plot information regarding the new story, but you'll be able to read it for yourself in less than three weeks. For those that haven't already picked up Full Dark, No Stars, it was a collection of four stories that was similar to what he did with Different Seasons and Four Past Midnight. You can find out additional information on the four stories and all of his works at his official website.