There is an ancient tablet pokemon with what look to be runes on it. It is ice/rock and can be found near a city with a windmill. It has the ability Flash Freeze which causes Pokemon to become frozen when they use a physical attack on it. The pokemon's name is Bitrunic and it knows the attacks rock smash and ice beam. It looks like a grey stone rectangular slab and the runes glow icy blue normally and red when it is attacking. It's eyes are two runes that are rectangles with diagonal lines that go through them.

The next is a steel/ghost type pokemon also found near the ruins that have bitrunic. It is known as the mirror pokemon. Named Flekter. Its pokedex entry says that it can trap a person's soul within the reflection. It does evolve into a broken mirror pokemon. I do not know the name of the evolution but it has a ghost like mist holding together broken mirror shards.

To get spewpa to evolve into vivillon, you have to shake your 3ds up and down while it levels up. You can do this at anytime once it is past level 16.
To get malimar, when inkay is leveling up past level 24, turn your 3ds upside down. Another thing to keep in mind is that you have to be surfing to do this.

There is a lady in Lumiose city who will give you a task once a day for a week. If you complete her tasks (it can be anything from showing her a certain pokemon or bringing her a certain item to showing her an evolved pokemon), she will give you an egg. This egg has a Skiddo in it. If you take the hatched Skiddo to her, she'll teach you how to ride pokemon. This isn't required to ride pokemon, but she gives you tips on jumping over ledges.

Pokemon-amie it a lot of fun to play and create bonds with your pokemon, however if you don't use it, your pokemon don't lose happiness. This is good because you don't have to use this feature. I can see this as being geared more towards girls.

Pokemon that can be found close to the starting area: quillom, bunnelby, scatterbug, fletchling, flabebe, pikachu.
The Togepi lineup loses its normal typing and becomes fairy type.

Metronome is now a fairy type move. There is a new move called Moon Dance that will raise a fairy type Pokemon's special attack. I mistook this for Lunar Dance earlier; sorry.

The day care center is near a bridge and has a river flowing behind it. You can now put up to four pokemon there. If you leave a pokemon there to breed, it's happiness will go down. If it gets too unhappy, it will no longer breed.

When you street pass someone you can see them on your PSS. You can also battle them in a place called the pokemon battle arcade (not to be confused with the battle arcade from the battle frontier).
Your friends don't believe you when you say you think you saw the legendary pokemon. Your rival (the male or female one that you didnt choose said they saw it too). Tierno says that you guys probably just dreamed it.

There are new types of pokeball, each with a different speciality. On has a yellow top with a lightning bolt on it. As you can imagine, it works well on electric pokemon. It is called the shockball.

The next is the ironball. It is all silver looking except a black band around the middle and a little indent on the top. Use for catching steel type pokemon but can also be good for catching heavier pokemon.

They are following the pattern of having two eeveelutions in this generation. I have seen the other and it is unexpected, but awesome. I won't say what type but it isn't dragon or poison like people are thinking.

Raichu gets a mega evolution. It turns brown with the orange/gold accents on its ears. Its speed and special attack are increased.

Tropius gets to mega evolve. It gains more back leaves and now has more coconuts hanging from its neck. Its physical attack is raised but its speed it lowered.

You can leave money with your mother again but you don't get annoying calls from her when she buys you stuff. Now you can leave her a shopping list and she will pick them up for you if she "finds a good sale".

The train tracks in the East of Kalos lead to a new battle frontier that is being "built" while the main story is happening. It presumably will be finished by the time you beat the elite four.

Shiny helioptile is a darker yellow, kind of orange-ish. This is the only shiny Pokemon I have encountered so far.

Talonflame doesn't evolve from Fletchling, there is a pokemon  in between.

The save game function takes substantially less time than previous games.

On the main menu, these are the options: New Game, Continue, Mystery Gift, Streetpass Settings, Options, Wifi Settings.

Mega stones can be found in a caves through a new feature similar to the mining feature in D/P/P. Not the exact same way, but you use your stylus to break rocks. You don't always find something but you can get mega stones (in their raw forms, you have to take them to the fossil lab).

You can design your own clothes (not the shape or anything, but you can add patterns or Pokemon images onto them, similar to how Tierno has vanillite on his shirt). You have to have seen the Pokemon in order to get it put onto a shirt. I am not sure if you can put any Pokemon on a shirt, but so far many of the early Pokemon work.

The 5th gym is Dark type and the gym leader is tough!

Just caught an Apparachnid. I can confirm the spelling! There is an empty spot right after it in the Pokedex, followed by Bitrunic. My guess is that is does indeed evolve. Upon further inspection, it has six eyes and the bottom of it's legs are blue. It is Ghost/Poison. 8.6 lbs. It knows a new move: Venom Spit (Physical attack, 50 base damage, 100 accuracy, can poison) along with Bite, Acid, and Poison Sting.

P.S. - Wednesday September 25th is the next reveal date from Nintendo. I think they will either reveal the second eeveelution, mega Raichu, or helioptile's evolution.