If what's been reported in Bloomberg and the Washington Post over the past two days is true, Fitzgerald has enough evidence to indict Rove and Libby as follows:
Karl Rove
Perjury
Obstruction of Justice
18 U.S.C. 1001 [The Martha Stewert crime]
I. Lewis Libby
Perjury
18 U.S.C. 1001
For Rove, the evidence is his lying to the FBI about his conversations with Cooper, and lying to the grand jury about where he learned of Valerie Plame's CIA association.
For Libby, the evidence is his lying to the grand jury about where he learned of Valerie Plame's CIA association.
Of course, just because there is enough evidence for an indictment doesn't mean there will be an indictment. There may be other evidence we don't know about which weighs in favor of Rove and Libby. Also, if Fitzgerald finds Rove and Libby to be more credibile than Novak and Russert, he may decide not to indict. "Prosecutorial Discretion" means that just because there is enough evidence to indict does not necessarily mean that a prosecutor will indict. (Which, by the way, is a lesson Ken Starr never seemed to learn).
All that being said, things look very very bleak for the White House right now. And this doesn't even get into whether there will be indictments for violations of IIPA or the Espionage Act (for which the noose seems to be growing tighter).
My view is that there is a 75% chance that there will be indictments of current and former senior administration officials at or around the end of the grand jury in October.