Tool appears to have announced that they will release their as-yet-untitled fifth studio record in May of 2012. This would be the first new material from the band since 2006's '10,000 Days'.
In typical Tool fashion, the band made the semi-announcement via a cryptic newsletter posting on their site, which also covered such topics as the Rapture and Taco Bell. You can read the full thing here.
An except from the newsletter reads as follows: "No matter how many new Tool tunes are currently complete, I will personally guarantee that the new CD will be released on May 22, 2012 (or May 15, 2012)."