Kid Icarus: Uprising, has closed its doors. A short message on the studio's website, translated by Andriasang, states that the company was closed on June 30 and that the website will shut down on July 31. Project Sora was started by Masahiro Sakurai, the brains behind Super Smash Bros, back in 2009.
Kid Icarus: Uprising, the only title released by the studio, debuted to reasonably strong sales and critical praise this past March. Sakurai is currently working on the next iteration of Smash Bros for the Wii U and 3DS with Namco. We've reached out to Nintendo for more information on Project Sora's closure.