It's only a 6(e) violation for a Government attorney or someone associated with one (including their investigators and agents) to disclose matters occurring before the grand jury. Witnesses before the grand jury and their attorneys are not under a secrecy rule. Transcripts of grand jury proceedings are not available to witness' lawyers before the investigation is over and an Indictment has been returned by the grand jury.
However, lawyers always debrief their clients after they testify and take notes as to what the client remembers being asked and remembers answering, and hope their clients are not mistaken or forgetting something. Defense lawyers are not allowed inside the federal grand jury room. They sit outside, and the clients are allowed to come out and talk to them during questioning if they have a question based on something the prosecutor has asked them. Lawyers can advise their client regarding the question, but they are not in the room to actually hear it. The client can come out as many times as is necessary.
When a client is in the grand jury room answering questions for several hours, it is doubtful they will remember every question asked and exactly how they answered, particularly if the prosecutor asks the same question numerous different ways.
So if you see that someone reviewed a grand jury transcript, first make sure the reporter got that right. And then realize it probably came from someone who is currently or formerly on Fitzgerald's team or was on Fitzgerald's team. If the article says the source "was familiar with" the witness' testimony or even that he or she "reviewed the testimony", they are probably talking about an oral recollection the witness gave his or her lawyers after testifying - and then the leak is probably from the witness's side.
But again, there is no grand jury secrecy rule for witnesses. Rove, Libby, Russert, etc, can all say what they remember being asked and remember answering. There is a total grand jury secrecy rule for anyone associated with the prosecutor --including lawyers, agents, court reporters, court personnel. etc.
There have been virtually no leaks from Fitzgerald's team. I expect everything that is leaked up until Fitzgerald makes his decision will be coming from lawyers for those who are or were subjects and targets.
One other note. It is not automatic that after an Indictment is returned, the defendants will get copies of grand jury transcripts. The prosecutor may file a motion with the judge seeking to release the transcripts to the defendants. If the prosecutor makes the request, it most likely will be granted.
The defense may file a motion asking the Court to direct the prosecutor to release the transcripts - as well as what is called "colloquy" - statements between the prosecutor and grand jurors, instructions given to grand jurors and the like. The prosecutor will usually object at least to the disclosure of the colloquy. The final decision is up to the Judge. Timing is also an issue - and as to the transcripts of grand jury witnesses who are listed as government witnesses at trial, the Jencks Act comes into play. That may become relevant down the road, but I don't see the need to bore anyone with that now.
Witnesses who have said they won't talk because of secrecy rules are not being candid. They aren't talking because Fitzgerald asked them not to and they are afraid to go against him. Particularly if they are under the umbrella of suspicion.