I'm glad someone posted this - I was stunned when I came across it. Personally, I'm quite happy that Atomic Edition is now part of my GOG library.
It is interesting that many GOG games are now heading over to Steam - For example, the Tomb Raider series as well as most of the Legacy of Kain titles. Now, Duke Nukem 3D and Shadow Warrior have been added to that list. Even so, I prefer the completely DRM-Free versions that GOG provides. Therefore, these Steam additions don't affect my GOG-based purchasing habits.
By the way, I'm extremely tempted by Pid for $4.99 - I'm a fan of GRiN's Bionic Commando: Rearmed, and I want to support Might & Delight. (The team is comprised of former GRiN staff.)
For the CAG's that have tried it, how fun is Pid?