Plenty of Steamworks games have been available pre-release, they just don't get "scene" releases by groups. There a bunch of P2P groups that basically specialize in hacking Steam titles now though, its common to get them ahead of time. I know people were playing Red Faction Armageddon a good two weeks before release for example. The only difficulty in cracking steamworks games is essentially getting the complete content files pre-release, the actual executable obfuscation is a joke.
Playing: Dark Souls 2: Scholars of the First Sin Watching: Mr. Robot