Here's a screen-grab of the mysterious "Jacob" seen (or not seen) in last night's Lost:
I lightened/sharpened/contrasted it quite a bit from the dark original, but it's still not quite as good as what I freeze-framed on the HD picture last night. You see the character has a high forehead, a fairly long head, long hair parted in the middle, a pinkish-salmon jacket/sweater over perhaps a khaki shirt or maybe a uniform. There's a flat, patrician nose and maybe a hint of a grey beard or goatee.
Doug (and others) think he looks like Ben. I think he looks somewhat like the apparently ageless Richard Alpert, especially how he looked when young Ben first ran into him in the jungle.
I think it's more likely that it's the Smoke Monster - or rather, a manifestation of whatever the Smoke Monster is - because of its apparent invisibility and ability to manipulate objects all over the room. I don't really think it's a figment of Ben's imagination, nor do I think he's pulling a fast one on everybody. I think there's a "there" there, but what it is is still indetermined.
What do you think?