Penny Arcade's On the Rain-Slick Precipice of Darkness 3 will come out for PC (Steam) and the Xbox 360 (Xbox Live Indie Games) on July 10th, 2012.
Some other details:
The price will be $5 for the PC version and 400 MS points for the XBLIG version.
Steamplay will get you both the PC & Mac versions (Mac version to come at a later date).
Mobile versions are still under way. Details on those will be announced later.