Damn.. I downloaded the HD version of the trailer last night and forgot to watch it.
Is it just me, or does it look like this one is in Liberty City again? I hope they release it for PC. Most likely we'll have to wait like 6-9 months after the PS3 release.
Definitely Liberty City and definitely New York City; the folks at Rockstar have always modeled Liberty City after New York City (much like San Andreas is supposed to be Los Angeles, or one of the surrounding cities in the San Fernando Valley). With the improved graphics for GTA IV, things like the Statue of Liberty and Empire State Building will be more visible. No word as to what Rockstar will call the Statue and Building, since I doubt they can use the real life names.