http://bulbanews.bulbagarden.net/wiki/2ch,_others_leak_heap_of_Black_and_White_info
See the big unconfirmed and rumour things on there? Bulbagarden's staff are mixed in opinion on this one at the moment. We're reporting on it simply because a number of sites have been running it as confirmed, but I'm personally leaning towards false right now.
Here's the low-down on why this is all up in the air.
1. When our staff were discussing this with the staff of other sites, they said they got this info from an inside source. If they got it from someone separate to Melkor of PokExperto, then the question is who, and how reliable they are as a source. They're refusing to reveal exactly who these sources are.
2. Serebii mentioned to RexRacer (the EiC of Bulbanews) that he had a number of the in-game sprites himself, however that Melkor had all the sprites. We've yet to see the sprites ourselves, so we can't confirm or deny if these are legit based on the info we have.
3. Melkor did get a big scoop with the previous generation in getting a full list of the new Pokémon names well before release (apparently from the same source Serebii had, they had a huge fight on the issue back then as I remember), which gives this a bit more credibility than it might have had otherwise.
4. The instant that these got out, multiple people were already claiming that they were fake and that they had been the ones to fake them, including different pictures of inspirations, etc.