I know I'm a few days late reporting about this, but some more bits of information on the Ruby and Sapphire remakes have been revealed. There's also a trailer out now that showcases some of the new features of these games. Take a look.
One of the biggest features of these two games are the new forms of Kyogre and Groudon. These forms are known as Primal Pokemon, and are said to be the the forms Kyogre and Groudon took in prehistoric times. The Primal form of Groudon will be a dual Ground/Fire-type Pokemon (which totally makes sense but also give Groudon a double weakness to Kyogre and other Water Pokemon). The process used to access these forms is known as Primal Reversion, and seems to work almost the same way as Mega Evolution. There's very little known about the details of this process, like if there's a special stone involved to activate the process. It's also currently unknown if Rayquaza will also have a Primal form.
In addition to the new Primal forms of Kyogre and Groudon, the rest of the Hoenn Region Starter Pokemon have also gained Mega Evolutions. The Mega form of Sceptile will be a dual Grass/Dragon-type Pokemon. Not shown in the trailer is a new Mega Evolution for the Legendary Pokemon, Diancie. From the picture I've seen, Mega Diancie has a very Sailor Moon feel to her. It's not known how the stone for this evolution can be obtained at the moment.
To see a picture of Mega Diancie, CLICK HERE
Another notable feature of this game is that the character designs for the members of Team Aqua and Team Magma have been redone. That's all there really is to report at the moment. I'll try and post more new information as soon as I find out about it.
EDIT: News has just been released that the Pokemon, Sableye will be receiving a new Mega Evolution in OmegaRuby and AlphaSapphire. This new form of Sableye seems to use a giant Ruby as a shield in battle. Considering what games this evolution is being released in, I have to wonder if Sableye will have a different Mega Evolution for each game. But this is just speculation on my part. Click on the above link to get a better look at this Pokemon.