Trivia from lostpedia.com:
* Jacob was portrayed in 3x20 by prop master Rob Kyker. (No word yet on who provided the face in 4x1 - assuming, of course, that it was Jacob's.)
* The voice that speaks the line "Help Me" in 3x20 belongs to executive producer Carlton Cuse.
* "Jacob" is J.J. Abrams' middle name. (Jeffrey being his first name.)
I've noted, as have many others, various meta-levels at work in Lost many times before. Jacob seems like an obvious target for more self-reflexivity of this sort, so I probably shouldn't be surprised by some of these details. And while I have to admit that it's likely a mistake to read Jacob more particularly as a trope on Abrams, Cuse, and company, (Though they do say that they have a "Bible" for the remainder of the show, don't they? Hmm...) I have to admit that it's awfully tempting.