Was Plame Outed SPECIFICALLY BECAUSE She Might Tell The Truth About Iranian WMD?

That's my guess.

According to current and former intelligence officials, Plame Wilson, who worked on the clandestine side of the CIA in the Directorate of Operations as a non-official cover (NOC) officer, was part of an operation tracking distribution and acquisition of weapons of mass destruction technology to and from Iran.

Speaking under strict confidentiality, intelligence officials revealed heretofore unreported elements of Plame's work. Their accounts suggest that Plame's outing was more serious than has previously been reported and carries grave implications for U.S. national security and its ability to monitor Iran's burgeoning nuclear program.

I think this was exactly the point. With the presumably honest Plame out of the way, the Cheney-ites could stove-pipe whatever bad intelligence they wanted in order to sell an Iran invasion to an unsuspecting US population.