In an e-mail sent out to GOG users who may wish to use the new GOG Connect service, they stated the following…
This is further detailed in section 13.3 of the GOG.com user agreement policy, where they break down exactly why the agreement was updated and what it entails for those who use GOG Connect and want to import their Steam library…
The GOG Connect is an experiment right now. Some publishers have been allowing their games to be connected from Steam to GOG, so that they’re DRM-free. Not every publisher and developer is on board with this, and some games may appear or may be removed from the list, so eligibility for importing games from Steam to GOG will be an actual work in progress.
The service so far has been popular enough that a lot of users managed to cripple the service when it first opened due to the load. Over the next couple of days it should all even out so that gamers should be able to conveniently move over certain titles in their Steam library to their GOG library. And no, you can’t buy a game on Steam, import it to GOG and then get a refund on Steam in hopes of keeping it on GOG. They have safeguards in place to prevent this feature from being exploited.
For more information be sure to visit the GOG Connect web page.