According to a recent post on Toolshed:

Though all has been quiet on the Tool front for some time, a promoter wrote in today to say he’s heard rumblings of possible Tool shows in 2009. We’ll keep an eye on this and keep you all posted.

Personally, I could maybe see a late 2009 tour, but that would be about it.  Presuming they maybe hit the recording studio soon, or early next year, then i could see a tour after a late 2009 release of an album.

Thanks to Scott, Tevin & Ganjalf for the tip.