Several questions on the Iran thing from a stream of consciousness perspective..
Plausible? Of course. The Departments of State and Treasury only recently accused Iran of harboring AQ terrorists. Iran has been running operations for years using the Revolutionary Guard and Qods Forces, with a proxy via Hizb'allah, the Saudi branch of that outfit once killing a number of our soldiers in Khobar Towers. So of course they could consider knocking off a Saudi diplomat in the US using Los Zetas proxies.
But why? What was to be gained from a hit on the Saudi Ambassador? Were they trying to start a regional war? If so, why use a drug cartel cutout? Will there be a new truther movement on this?
Good fortune.. how likely is it that the Iranian-American tasked with the plot would stumble onto Los Zetas, and specifically onto a DEA mole? Was this perhaps some kind of 'good deed' done by the cartel to make points? And how likely is it that Iran would trust someone with such a plot who was not an intelligence agent? Or maybe we know all their agents.
NSA. Were they listening to this Iranian-American's calls? Is their a civil rights violation in that? When did they know he was involved in the plot?
CIA. Where were they? The event was carried out via foreign operators involving a belligerent country, targeting an Ambassador. We must presume there was CIA involvement, but perhaps we shouldn't.
Timing. Yes, Holder was on the verge of being subpoenaed on Fast and Furious when suddenly comes this plot involving a Mexican drug cartel. Interesting, if nothing else. But Holder has an interesting past. Also, it's fortunate that A'jad just released the two 'hikers' held in Iranian custody. Surely this story would have never seen daylight had they still been locked up. So who actually paid the million dollar ranso, er, bail?
Revenge. Let's speculate wildly that Obama released this story to knock attention away from Fast and Furious, Solyndra, his defeated jobs bill, etc. That would be the ultimate 'wag the dog' since it would require a public indictment of Iran. They actually promised to take 'appropriate action', something we haven't been able to do since Beirut. So Iran can't be too worried. By the way, imagine Bush or Cheney making this bust and then saying they would take appropriate action. The lefties and the crazies would be apoplectic, and Joe Biden would already be urging the House to start drafting the impeachment articles.
So it sounds like a very risky move just to score points, unless 1) this president is really desperate, 2) it's on the up and up, the timing is an innocent coincidence, and they hope this will put international pressure and embarrassment on Iran so they can reach a deal on the nuke program, or 3) this kills two national security birds with one stone. The other bird? Who knows, unless it's a way of telegraphing that certain other "birds" will soon be flying.