Time's Matthew Cooper Will Testify

AP is reporting:

Time magazine reporter Matthew Cooper agreed Wednesday to testify about his sources in a government leak of a CIA agent's identity, a dramatic about-face which came as he faced going to jail.

"I am prepared to testify. I will comply" with the court's order, Cooper told U.S. District Judge Thomas Hogan.

What does this mean for Karl Rove? That's all I want to know.