Since promo copies are out, and they report very few glitches (if any). My bet is that the release is imminent. I only believe Leatherneck is looking for good bank accounts in a small country somewhere so they can stash all the money they're gonna earn.. ;)
And it's better for Leatherneck to sell through their "own" channels first, Steam take a pretty good chunk of the money. So I'm guessing late august.