Re your question, "How important is this to the case?"
My answer is, I don't know, but the above article's assertion that Wilson "shattered a pillar of President Bush's rationale for war" is a baldfaced lie. If the article contains such a big lie, why should I believe anything else it contains?
The identify of these two CIA agents was revealed weeks ago in a pre-trial hearing (IOW, it is NOT new news). Furthermore, the testimony of the CIA agents will demonstrate that the LIAR here is indeed Joe Wilson; with the agent stating that it was Wilson's wife who sent him to Niger, not the VEEP. Fitzy's case is falling apart quickly; now when will the judge dismiss all charges and throw the persecutor in jail for misconduct?