In an article by Kat Bailey posted on 1up.com on January 31st, 2011, Nintendo of America's localization coordinator Joel Simon explained that Dream World will not be available when Pokémon Black and White launch in March. Below are portions of that article pertaining to the Dream World launch.

Pokémon Black/White: How a Pokemon Comes to America

When Pokémon Black and White arrived in Japan late last year, it brought a few intriguing new features to the table. They included new IR functionality that dramatically streamlined battling and trading; the ability to upload Pokémon into a digital cloud called the "Dream World"; and passive wi-fi functionality that allowed commuters to peek into other games and pass around stat boosts.

Nintendo is looking to Japan for inspiration in other ways as well. Last year, the God Pokémon Arceus was distributed via the Dream World following a fan poll, and the American branch may also do the same. GameStop and Toys 'R Us also figure in the equation, with the former currently in the process of releasing special versions of Entei, Raikou and Suicune that can be used to unlock the new Pokémon Zoroark.

And then there are the new online features, which figure to have even more appeal to western audiences than those in Japan. Simon acknowledged as much when I spoke with him, telling me that he expects the Dream World to be more popular in North America than in Japan. It's the Dream World that makes it possible to upload a Pokémon into what amounts to a browser game, with the prizes including Pokémon with special abilities and other perks.

As in Japan though, it looks like the Dream World won't be available at launch. While Simon didn't go into specifics, the assumption is that Nintendo wants time for more stress testing to avoid a repeat of the Japan launch, where the servers were immediately hammered into oblivion.

"It's currently scheduled to launch in the spring," Simon told me, which suggests that the Dream World will launch around a month after Black and White arrive in North America.

Source: http://www.1up.com/previews/pokemon-blackwhite-coming-america