Looks like there were at least two leakers: a kind one who released Cooper from a pledge of confidentiality; and a hard one, who leaked to Miller and doesn't seem inclined to spring her from a stint in the joint. Note if I recall correctly, everyone on Bush's staff released Cooper and Miller from any pledges long ago.
via Drudge: "I went to bed ready to accept the sanctions" for not testifying, Cooper said. But he told the judge that not long before his early afternoon appearance, he had received "in somewhat dramatic fashion" a direct personal communication from his source freeing him from his commitment to keep the source's identity secret.
As for Miller, unless she decides to talk, she will be held until the grand jury ends its work in October. The judge speculated that Miller's confinement might cause her source to give her a more specific waiver of confidentiality, as did Cooper's.