Plame investigation

Karl Rove admits circulating and discussing 'damaging information' about CIA operative Valerie Plame, but denies being the source of the leak to Robert Novak (Murray S. Waas article at The American Prospect website, March 8, 2004.):

Rove and other White House officials described to the FBI what sources characterized as an aggressive campaign to discredit Wilson through the leaking and disseminating of derogatory information regarding him and his wife to the press, utilizing proxies such as conservative interest groups and the Republican National Committee to achieve those ends, and distributing talking points to allies of the administration on Capitol Hill and elsewhere. Rove is said to have named at least six other administration officials who were involved in the effort to discredit Wilson.

Why aren't these people heading to federal prison already?