I e-mailed Bill Roggio about it this afternoon, after the Stratfor rumor started crackling but before this bombshell-if-it’s-true from CBS hit the wires. His verdict: “If he was dead we’d have known by now.” Enter … the note:

CBS News has obtained a copy of an intercepted letter from sources in Pakistan, which urgently requests a doctor to treat Zawahiri. He’s believed to be somewhere in Pakistan’s remote tribal areas of Pakistan…

It is reportedly written by local Taliban leader, Baitullah Mehsud, whose signature and seal are visible on the letter.

The Taliban logo and the Mehsud’s seal have been confirmed by experts as legitimate.

However, CBS News has not been able to confirm the authenticity of Baitullah Mehsud’s signature and seal.

The letter is dated July 29 – one day after a U.S. air strike that killed al Qaeda weapons expert Abu Khabab al-Masri, and five other Arabs in South Waziristan.

Bogus communiques from jihadi home base aren’t unheard of; the classic of the genre is a December 2001 Egyptian “obituary” for Bin Laden featured prominently on any 9/11 conspiracy website worth its salt. But it also wouldn’t be unheard of for a U.S. airstrike like the one that took out Abu Khabab earlier this week to have netted a bigger fish in the process. These guys do get together periodically, which is why speculation continues to swirl that the missile that killed Abu Laith al-Libi in January also killed Adam Gadahn. Nothing to do now but wait and hope, bearing in mind that we’ve tried and failed before to get Zawahiri but also that (a) it’s unusual for two credible sources like CBS and Stratfor to be hearing the same rumor and (b) we’ve had some unusually high-profile successes in targeting these cretins over the past six months or so (Libi and Khabab being the two biggest scores). Just a coincidence? Maybe not. From an L.A. Times piece in May on the airstrike that nailed Abu Sulayman Jazairi:

The increasing success and pace of airstrikes this year indicates that American spy agencies and their allies have made progress in infiltrating Al Qaeda in Pakistan, said Louis Caprioli, a former anti-terrorism chief of France’s DST intelligence agency.

“You have to have good intelligence on the ground to hit a target like that,” Caprioli said. “It requires human as well as technical intelligence. I think the money that the Americans are spreading around is having an effect.

“Also, there are troops in Afghanistan, prisoners being interrogated. This is a long-term effort that is paying off.”

How big was the payoff this week? Stand by for possible glorious updates.