According to Redstate, a very good source has confirmed that Chief Justice Rehnquist has retired from the Supreme Court today.
There are additional rumors that Justice Stevens may also retire soon.
Update 7/14/05: Rehnquist, after spending the night in a hospital, said the following:
“I want to put to rest the speculation and unfounded rumors of my imminent retirement,” the statement said. “I am not about to announce my retirement. I will continue to perform my duties as chief justice as long as my health permits.”