I have a question, how legal would it be to release classic arcade games emulated under MAME? I think the arcade was a big part of our childhood gaming, and I think that it would be a shame not to preserve them. You could package them the same way that DOSBox games are packaged.

Alternate question. IF GoG is able to release MAME-emulated classics, what are the games you would want to see released the most?

MAME's license forbids commercial use; the page mentions exceptions being possible but it's not clear how viable that would be long-term. There's also the problem of arcade games being built around a coin-operation mechanism; with emulation you can essentially play forever so there's no challenge unless you set a self-imposed limit.

GOG has one arcade release, Raiden Legacy, which is a port rather than emulation. There are similar ports on other services. If GOG gets more games like this in the future they will probably also be ported in some way rather than directly emulated.

In other words, it is possible if GOG obtains the rights to distribute the games. Since, that is what GOG does anyways, the only real hurdle is asking them about long term agreements, and showing them several proofs of permission.

I know that this proposition is unlikely, but one can always dream, and it's worth throwing the idea out there.

Wasn't DotEmu selling some Irem arcade titles? I guess that those games are nothing but roms wrapped with MAME or the like.

You're correct. The Raiden Legacy games are roms in a MAME wrapper. In fact, the reason Raiden II isn't part of the package is because no one's been able to properly decrypt the rom data. A PC version of Raiden II exists, but I hear it's inferior. I'm actually thinking of just taking the roms out and loading them up in MAME so I can save-crawl my way to the end of the game. There's no other way I'm gonna be able to finish the Raiden games. :P
So basically, it's on a game by game basis if GOG or DotEmu could bring arcade games to PC. They would need to both secure permission to distribute the games as well as find the right technical solution to bringing them to the PC.

It seems to be their own custom built emulator, and it is poorly optimized (even worse so than SEGA's Mega Drive/Genesis emulator, and that is saying something)

A while back I noticed there's a number of arcade classic collections available for the pc. I wonder if GoG could get the rights to collections such as these:

http://www.amazon.com/Namco-Museum-50th-Anniversary-Collection-Pc/dp/B000AAQZPE/ref=sr_1_10?s=videogames&ie=UTF8&qid=1376049579&sr=1-10&keywords=namco

http://www.amazon.com/Capcom-Arcade-Hits-Three-Compatible/dp/B000E4N1CQ/ref=sr_1_8?s=videogames&ie=UTF8&qid=1376049604&sr=1-8&keywords=capcom+arcade

http://www.amazon.com/Taito-Legends-2-Pc/dp/B000RHLTD8/ref=pd_sim_vg_4

http://www.amazon.com/Midway-Arcade-Treasures-Deluxe-Edition-Pc/dp/B000BH3DC4/ref=pd_sim_vg_5

Quite a few others too, but I linked collections by Namco, Capcom, Taito, and Midway. Several of the out of print disc versions seem to be rare and pricey these days.

The biggest problem with those (at least in my book) is that the formats are usually either opaque, or the rips they use are out of date and thus may not emulate correctly. I wish Star ROMs was still around, but they didn't last very long and I know they had some issues with licensing, so I doubt gog would want to go down that rat hole.

Those are fair points, although you can require emulated currency and GOG could presumably work out a deal with the developers.

That being said, they'd also have to convince the owners of those games to license with GOG. MAME itself is sort of quasi legal in that a lot of the folks playing those games don't actually own the boards for them. And the boards themselves are rather hard to come by.