Aspyr, who are publishing the Mac OS X port of Civilization 5, have a page linked in their primary navigation for their store entitled “About DRM”. The contents are remarkable for how not-a-big-deal it is written:
Customers may download the game up to 10 times. This includes if you mess up and “re-download.” If you run through those 10 downloads, call our customer service folks (support.aspyr.com/ 512.708.8100) and they’ll help you out. Impatience and a poor network connection could lead to using up more than a few.
They admit that the odds are high their YOU ARE A CRIMINAL lockout system will kick-in for no good reason at all, and they’re pretty ok with this, so why aren’t you?