I doubt there are 23,300 possible permutations. Moreover, I doubt a Googler wouldn't think of this classic before leaking his e-mail. Any other theory? Perhaps no one was fired and it's just link bait?
Assuming a worst case of two possibilities for each difference, that comes out as ceil(log_2(23300)) = 15 differences necessary. You could easily get that by swapping out words for synonyms (especially if you use more than two synonyms per difference).
Most likely somebody just forwarded it to their favorite blog, especially if they didn't think the email was confidential. Pretty easy to track outgoing email.
With "CONFIDENTIAL: INTERNAL ONLY GOOGLERS ONLY (FULL TIME AND PART TIME EMPLOYEES)" at the top it's hard to believe they might have thought it wasn't confidential.
I heard from a Googler before the article came out that the leaker was fired. While one could imagine a second, as-yet unleaked email about the fake firing, isn't it much simpler just to assume that the leaker was fired?
You'd need over 14 binary manipulation choices, but only about 9 if you had a choice of three. If you include word synonyms in the choices, with over 250 words in the memo, I don't think it's unreasonable.
