The Pew Internet and American Life Project has taken it's first exclusive look at Twitter.

In a nutshell:

• 8% of online Americans use Twitter
• Those 18 - 29 are more likely to use Twitter than older adults
• African-Americans and Latinos are more than twice as likely to use Twitter than whites
• Urbanites are twice as likely to use Twitter as rural dwellers
• Women and and the college educated are also slightly more likely to use the service.

You can read and overview and download the full report at the Pew Internet site