The sale is not on yet, but the developer is going to be releasing some free DLC for the game this weekend and has timed a Steam sale to coincide with this release. I'm betting on the game dropping tomorrow around 11:00am Eastern. That seems to be a magical time for Steam's weekend sales although they don't always adhere to it. Support indie developers!
EDIT: Looks like I was off on my time estimate. My new guess is that they are going to update the price when the DLC goes live. Here's hoping.
Edited by campbelld, 26 June 2009 - 04:26 PM.