The Pokemon Global Link - a website that offers added online functionality to Pokemon Black and White - was originally scheduled to go live on March 30 for North America and Europe. This is no longer the case.
"As a result of the earthquake in Japan and the need to conserve energy resources, the launch date has been temporarily delayed," writes the temporary site. "When a new launch date is determined, it will be published here on the Pokemon Global Link."
So, no access to the Global Battle Union or Dream World for a while. Both of those will make for some great post-game content, but considering how huge the main game is, I think we can manage for the time being