Re: TF3 Trailer On-Line @ 4:00 PM PST

Personally, I think the bot is Sentinel Prime. His head vaguely looks Optimus-ish to me, and I believe during one of Sam's ramblings in ROTF, he mentioned "Sentinel Prime's expedition" or something along those lines. Perhaps during this "expedition", he crashed on the moon.
Just a theory.
Just a theory.