Also, GOG has been cryptic throughout the day, saying there will be an announcement on the 22nd. Wikipedia has fixed itself to reflect this. Given the circumstances, I somehow doubt that this announcement will be a pleasant one. Rumors are floating that this might be a PR stunt. If this is the case, someone needs a new director of marketing.
I really can't imagine they would be stupid enough to do this as a PR stunt. Even if they are launching a "GOG 2.0" or something I can't believe they would just close down the original site with no warning and put up that message. Of course if they are actually closing and gave no warning, that is even worse. Either way a bad decision.
One rumor is they are joining another digital download site, like GamersGate or Steam, and will run a "GOG section" on that service. That would pretty much be the only thing that would make sense of this, as it would make sense to shut down the original site in that instance. Still, as I said already, the site shutting down out of nowhere is an excellent example of why having no DRM is a great thing in the first place, so if they relaunch on Steam or something it will only make their adding DRM to the games a more obvious bad thing.