Pokémon Omega Ruby and Pokémon Alpha Sapphire announced

European demos contain Mega Glalie. which i'm guessing means the US demo has Mega Steelix.

Demo Spoilers:

 Spoiler

First playthrough you get Mega Glalie/Steelix, on playthroughs after that you go on an adventure to different small islands, it seems like there are 3 or 4 different kinds of islands with basic objectives like "beat all the trainers" or "find the missing pokemon".

each time you complete an island the demo ends and you unlock something, like NPC's showing up in Mossdeep and gifts that can be traded over to the main game. One of the rewards are pokeballs, one is heal balls, and you can get heart scales too. yeah the rewards are pretty shitty.

On your tenth playthrough you fight a boss trainer who has Blaziken, Swampert, Sceptile and Hariyama. 10 playthroughs unlocks everything.

I kinda wish the demo hadn't been spoiled for me (I checked Serebii to relay the info about the US demo, and caught it just as Mega Steelix was revealed) but eh, I would have hated playing through the demo 10 times for such crap rewards anyway *shrug*