I have not found an embed version yet but Rockstar has released the new trailer
for GTA IV. The city is
Liberty City and it looks like you're playing a russian mobster. Not sure of much but the trailer does look good (not quite blow you out of the water great but Rockstar games really aren't about the graphics). No gameplay is shown but the trailer is pretty slick.
Update: My bad, it's Liberty City...missed all of the little tells in the trailer