Updated: According to a recent Pew Internet research report, large percentages of Blacks (26%) and Hispanics (18%) are using status updating services, like Twitter, on the Internet. (Pew said they had insufficient statistical data to measure the usage rates of Asian-American users.)
Much of the involvement of African-Americans and Hispanic Internet users is likely tied to their heavy involvement in social networking sites and mobile Internet usage, both of which are closely related to the use of status updating services.