Are celebrities hijacking Twitter? What does that mean for your brand?

Three months ago the most popular Twitter member was tech blogger Robert Scoble; he had 6,900 followers in January of this year. Meanwhile, actor Ashton Kutcher topped one million followers this morning beating out CNN in a race to see who could reach the milestone. He will join Twitter co-founder Evan Williams on the Oprah Winfrey show today to talk about the micro-blogging service. Word has it Oprah, who joined Twitter yesterday, will send her first tweet today. Kutcher and Winfrey are t…