The adorable bunny thing in the image is Victini, the latest Pokémon to be announced for Pokémon Black/White. He/she/it is also the first Pokémon to officially receive the number 000, making it either one of the first Pokémon's ever identified or just bad at math.
Japanese players will be able to obtain Victini from September 18 to October 18th, at their local DS Download Stations. From there players will receive the Liberty Ticket, which will let players encounter Victini in game at a certain point. How, when, or where in game hasn't been disclosed, but finding rare Pokémon is half the fun anyway.
No word on when the rest of the world will gain access to Victini, but those familiar with prior Legendary releases should expect the same treatment (Toys R Us or The Nintendo Store). We'll be sure to let you know as soon as we find out.