The February issue of The Sneaker Magazine is announcing that the two volumes of Nagaru Tanigawa's The Surprise of Haruhi Suzumiya light novel will ship on May 25, 2011! According to the announcement, the two volumes will ship simultaneously in Japan and "the world (outside Japan?)."
This new volume of the light novels will be the first new one in four years. The last story in the series was The Dissociation of Haruhi Suzumiya, which shipped last April 2007. The 10th volume was initially announced to be released on June 1, 2007 but the release of a notice of delay with Haruhi saying "Gomene..." surprised fans. I guess we should wait a little more for this volume!
The Sneaker had said in April that the Kadokawa Sneaker Bunko imprint would publish the next novel within the year. They later clarified that "within the year" meant within 12 months of the announcement, not within the year 2010. However, the new May 2011 date is after even the clarified schedule Kadokawa had laid out for itself.
Source: Moe Ota-News SokuhÅ via ANN, MyAnimeList