Secret Orders Target Wikileaks Backer's Email

The Wall Street Journal says that the government has obtained a controversial type of secret court order forcing Google to turn over information from the email accounts of a WikiLeaks volunteer.

The court clashes in the WikiLeaks case provide a rare public window into the growing debate over a federal law that lets the government secretly obtain information from people's email and cellphones without a search warrant. Several court decisions have questioned whether the law, the Electronic Communications Privacy Act, violates the U.S. Constitution's Fourth Amendment protections against unreasonable searches and seizures.

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How would Google know the IP addresses of the recipients of these emails to comply to the court order?
I thought all Google could see was the email alias and domain name of the recipient's email system.
The recipient's IP addresses are usually unknown, unless the recipient is also a gmail customer, or they are using IM, right?

I suspect the U.S. government will not find much useful stuff in gmail, I hope any person involved in Tor and Wikileaks is not using U.S. based email systems for such correspondence.

Google knows everything.