In an article which appeared on MTV nearly 2 months ago, MTV have possibly confirmed for us that Grand Theft Auto 4 will use the Rockstar Advanced Game Engine (RAGE). I'm unsure as to why this hasn't been picked up until now, but it's certainly great to hear, the article cites the following:
...the Rockstar reps explained that the game was running on RAGE. This is the graphics technology gamers are to expect from future Rockstar games, including the next "GTA."
If you head over to http://www.rockstargames.com/tabletennis, you'll be able to see some of the awe-inspiring realism in the screenshots provided, as well as the HD videos.
The next instalment of the ground-breaking series we all knew would feature much improved graphics, but knowing that the game will make use of RAGE is brilliant news. Of course this isn't set in stone, as we don't have official word from Rockstar on this, but it seems quite likely to happen.