Hrm. So there's something going on over at DRM-free digital distribution site GoG.com. The site is down, and in its place a message that, in part, reads: "We have recently had to give serious thought to whether we could really keep GOG.com the way it is. We've debated on it for quite some time and, unfortunately, we've decided that GOG.com simply cannot remain in its current form." (And the message seems to have changed since I read it earlier, which is interesting.)
However, it's not necessarily over, and there will be a solution for everyone to download their games. We contacted the GoG team and received this message: "As the message on the site says, this doesn't mean GOG is gone. We'll have more to share in the coming days." So we wait and see. My guess? They'll be assimilated into another digital distribution system, something like that.
EDIT: This unfortunately-timed Bit-tech article is worth a read.