Me thinks we've found the skunk:

The e-mails surrendered by Time Inc., which are largely between Cooper and his editors, show that one of Cooper's sources was White House deputy chief of staff Karl Rove, according to two lawyers who asked not to be identified because they are representing witnesses sympathetic to the White House. Cooper and a Time spokeswoman declined to comment. But in an interview with NEWSWEEK, Rove's lawyer, Robert Luskin, confirmed that Rove had been interviewed by Cooper for the article. -- Michael Isikoff, Newsweek

Rove seemingly being a Nixonian rat fink. Raise your hand if this news is much of a surprise....

UPDATE: Good points made here.