Even though the achievements aren't named yet, I'm pretty sure that with both Vanilla and G+K some of them accidentally got revealed early, allowing us to find out some additional stuff before it was officially announced. So yeah, might as well keep an eye on them just in case someone slips up.
Yeah, there was a way people found them early. I don't remember how though. I think some xml code on Steam somewhere. There's a lot of websites that mine Steam for new data though. It's bound to get out when Firaxis actually puts in the proper names and descriptions.
This could also be a sign that beta has started. =) Even if it's just a test version of the game, they might have early achievements there. I know Steamworks games usually do betas through Steam. They create a separate, private version of the game and only allow certain Steam accounts (the beta testers) to download and test it.