A Googler, John Mueller asked a question "is it safe to launch a new section of a website with tons of content at once or smaller chunks of the section should be taken at a time"?
Matt Cutts said that Google can handle it either way. If a site releases hundreds of thousands of pages overnight, Google may raise a red flag and the Google spam team might perform a manual review. If you do not want to draw Google's attention to your site and have the team manually review your site, do not release too many pages too quickly.
Matt suggested that a slower roll-out of the content in larger block will not bring your website into notice. He added that it is a rare case that a site releases a large chunk of new pages with unique and quality content at once. Matt believes that it is somewhere impossible.
Watch the video:
Webmaster Central Blog:http://googlewebmastercentral.blogspot.com/
Webmaster Central:http://www.google.com/webmasters/"Should I Add an Archive of Hundreds of Thousands of Pages All At Once or in Stages"? - Google Webmaster Video has the Answer!,