You can now pre-register for the Rockstar Social Club using your Xbox Live gamertag and/or PlayStation Network ID. The Social Club will fully open once GTA IV is released, and will provide all kinds of statistics on your game progress. There are even prizes for those who complete the game the fastest. See our original news story for all the details.
The website states that early adopters who pre-register before April 29th will be rewarded by being automatically entered to win a special once-in-a-lifetime prize for true GTA fans: your portrait custom drawn by Rockstar Games in the signature style of Grand Theft Auto IV's illustrations. You'll need to be aged 18 or over, and reside in one of the following countries: United States, Germany, The Netherlands, New Zealand, Switzerland, or the United Kingdom. For more details head to the sweepstakes page.
Link: Rockstar Games Social Club