Thats mildew resistant drywall, some brands it's green.
Good choice on the drywall btw.
Yep, just what the local Menards carrys for mold & mildew... MagniKhan got it right
I actually wanted to use: http://www.usg.com/sheetrock-glass-mat-mold-tough-firecode-x-panels.html
But they're $25+ a sheet