Ok, I don't normally follow this series or anything, but I watch it on Cartoon Network occasionally. I thought I saw what seemed like the last episode a few days ago. Spoiler tags follow for those who don't know the series...

Al had been restored to his human body, but he was 10 again and had no memory of what happened in the past few years. Ed somehow wound up in Munich, year 1921, where alchemy doesn't appear to work or something. I'm assuming that Ed was on the other side of the Gate, which he had claimed was Europe or something earlier in the episode. I'm not sure what exactly happened, but the boys were seperated, Ed was still missing his arm (maybe his leg), and it seemed like the series was over.

Was it? Or is there more FMA which I don't know about?

There's the movie "Fullmetal Alchemist: The Conqueror of Shamballa" which closes off the series, and continues where the TV series left off.

Whats with Ed's fake arm in the 1920s? Did they have things like that

They didn't. Or we wouldn't have to mess with developing bionic limbs and stuff now. I'm pretty sure that it's said in the movie that Ed's stash of prosthetics was made by Hohenheim. And IIRC, supplemental materials for the show say that Hohenheim was partially responsible for the initial development of Automail in Amestris as well, hence why he'd have that knowledge in the first place.

as far as I remember, thats right. thats why Eds prosthetics are different than automail, but still light years ahead of anything we've seen.

The "skin" that Ed wears over his prosthetic arm, however, is authentic German tech though, as shown when he was being fitted for it in the clinic. I'd assume that Ed kept that arm fairly limp during those checkups, to avoid being questioned about the mechanics of that arm, though. That automail of his would have been a hot commodity, otherwise.