Well, that's what you first see when you load Fallout 3 IIRC. Anyway, given there's an ESRB logo on it (albeit Rating Pending), they must have something they're about to submit since, under the rules, once you slap an ESRB rating on your ads, ALL ads going forward MUST sport it, and you MUST have the final rating before you go live.
OK, saw the trailer. Vault 111 will be the initial setting. And it looks like my second guess was right. If the Paul Revere statue (and retrofitted USS Constitution) is any indication, we're talking Boston here. Which means we're definitely talking the Commonwealth. Also the Brotherhood of Steel, IINM by one of the powered armor shots.
That now leaves the question on the identity of the Player. For the record, here's the list of past IDs:
1 - Vault Dweller
2 - Chosen One
3 - Lone Wanderer (NV didn't have a vault dweller, so was instead just called "Courier")
I'm still banking on "Sole Survivor".