You can view past images at the WTC Progress cam - but - it's not too easy to tell if it's lit blue/white.
There is a calendar on the side, and you can select the time of day you want to view from there.
Back to 1 WTC and the new steel... It looks like they have started to put up blue netting around the new steel, and they're almost done cladding the current floor on the south side. I bet they'll finish that today (not much left to clad now) and start on the next floor on Carlos' side. Carlos - would you be able to verify the first part with a photograph?