The game has now essentially been finished. Rockstar are just polishing some things and dealing with bugs and other minor things.

The release date has yet to be decided. "Before the end of April" is all we know. The gaming press will receive a hands-on preview before then (about a month from now).

The Liberty City map was shown briefly during the demo. Kikizo
describe it as containing a large island in the middle (Algonquin) with Alderney to the left (similarly sized) and two islands to the right - a small one (Bohan) up north with Broker and Dukes underneath.

Liberty City will contain a subway system, which Niko is able to use. The system covers - at the very least - Broker and Algonquin, but we aren't sure about the other areas yet.

Rockstar commented on the map found in Trailer 3 by forum member "Bluespot". "My God!" was their reaction. In other words, yes, it is the map

A speedboat journey around (approximately) half of Algonquin lasted for 5 minutes.

In terms of camera views, all the traditional views are still there, and there will now also be a dashboard view.

There is a new character called Bell.

During the demo, they passed a restaurant called "Poop Deck," where they met with Francis McGreary. Other places mentioned are Oneida Avenue, 99 Long Road (Broker), a bar called Perestroika, Koreatown

The character Brucie is introduced to Niko by his cousin Roman. Brucie runs a garage just around the corner from Roman's taxi depot.

Characters also often look different each time you see them instead of perpetually wearing the same clothes like in previous GTAs.
The red and blue search radius on the radar is centred around the point where the crime was committed, and your last known whereabouts.

You can smash your own car window to enable you to shoot from it; you can free-aim outside of your window using the right analogue.

Liberty City has one airport, based on JFK, called Francis International Airport (yes, it's the same name given to the airport in GTA3).

Progress is automatically saved after completing a mission. There are also safe houses dotted around the city, which you can save at any time.

In this demo, the cell network is called Badger, whereas in the last one it was called Whiz.

Building relationships with characters is important. During the preview, Jacob comes to meet you rather than vice versa. This is only possibly once your friendship with Jacob has reached a certain level.

Pool, eating, darts, and bowling are just some of the activities possible in GTA IV. The cellphone is used to access these activities.

There is a radio station called IF99.

The game clock is no longer one minute = one hour. It's now two minutes = one hour. So days are now longer.

One of the missions previewed during the demo is called "Deconstruction for Beginners". A new character called Playboy X is introduced by Elizabeta (who happens to be a friend of Niko's). Playbox X is one of the characters who provides missions in the game. He lives in a mansion.

The new targetting system was previewed. There are eight purple segments in the target circle that make up someone's health, which you get when you're locked on - during free aiming you don't get the indicator.

Another mission called Truck Hustle was previewed. Two new characters are introduced during this mission - Ray, a mafioso character, and Bell.

The more "expensive" cars have better GPS systems than poor ones. The one in this preview "talks us through the streets."
The cellphone can be used to listen to radio stations.
The GTA4 weather system does not feature seasons, which means no snow

GRAND THEFT AUTO IV - GTA IV previews go live! 10 new screenshots released. (News)