A recent post on Nintendo of Europe's Twitter reveals that the recently announced Pokémon Black and White 2 will be released in Europe "this autumn". The games will be released in Japan in June.

This release date is sooner than many expected. There has been no word on Australian or North American release dates.

EDIT: A press release on Nintendo of America's website confirms that Pokémon Black and White 2 will be released in North America "this fall". A brief advertisement of this may be seen below: