I would imagine this is a sort of policy conversation that the VP could legitimately have with any significant staff member with clearance. This is leaving aside the fact that Plame was not a covert agent then anyway, and furthermore that there is no indication he knew that she ever had been. It must have been Tenet who gave him the name and the fact that she had recommended her husband for the job, indicating that she was an employee of the CIA (which she was, at a regular above-board desk job). So what's the big deal?
Rush just pointed out how utterly absurd it is to think THE VICE PRESIDENT can't/should'nt speak of matters of the US with his staff.