It hasn't closed its doors yet but the site is down now. However; there are rumours that it is just a bizarre PR stunt and they are simply leaving 'Beta.'

I think it's very likely that it's just a PR stunt. Quite bold and strange one, bound to piss many people off.

The wording on the site certainly does sound like they are going to put something different up instead.

Its not abandonware if its up for sale.

software that is no longer sold or supported by the original publisher / developer, often found as free downloads on the internet because it cannot be obtained elsewhere. Not legal, but often seen as morally acceptable because the company that made it is no longer selling the title, nor releasing it as freeware, therefore abandonware is "keeping the game alive", so to speak.

I'm quite sure that Atari made some bucks from MoM, as holder of the rights, sales in GoG.

Where is Master of Magic currently for sale?

Just because the shop is not owned by the publisher, does not mean that the publisher does not sell it anymore. And no, you cannot just take "trash" software and sell it. the copyright holder has to agree otherwise you would get sued. you get the license to use the software from the publisher and not from the shop.

You can get it on Amazon for $135.88  

So um ... did GOG.com have a legal right to sell MoM or not??

I'm writing  this down to use somewhere :]

Yes, GOG has the rights to sell all of the games that they offer. It's a legitimate business run by CDProjekt, the makers of The Witcher.

And it's confirmed today that this was a publicity stunt. They are relaunching, out of beta, Thursday. With new releases such as Baldur's Gate.

Well, it turns out it was a marketing stunt. I'm glad it wasn't real, but I hate being fooled.