Far Cry 2 originally shipped with SecuROM which was apparently rendered inert by the 1.03 patch. Upon installing the GOG version on my Windows 7 machine, I note that there's a SecuROM registry setting under:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Ubisoft\Far Cry 2

This by itself may mean nothing but I was wondering if anyone has tried the SecuROM removal tool to confirm SecuROM has been rendered inert on the GOG version as well?

Addendum: For what it's worth, I've used the SecuROM Removal Tool and it appears no SecuROM components are installed with Far Cry 2.

Sounds to me like the game itself installs that key for the SecuROM binaries to read.