PlanetGrandTheftAuto.com says that

the Dutch magazine Power Unlimited and the Australian Official PlayStation 2 Magazine have confirmed the following details:

• "Menace" is a mission name (from "Menace II Society).
  
• "Reece's Hair Facial Studio" is one of the barbershops. The barber's name is "Old Reece."
  
• 35%-50% Increased Polygon Count over Vice City
  
• St. Brutus Motel is one of the buildings in Los Santos.
  
• Dan Houser said, "It's the third part in a loosely held together trilogy that started in 2001, that went to the mid '80s and has now come to the early '90s.".
  
• Cars accumulate dirt.
  
• Tractors are confirmed.
  
• Real-time reflections on some floors, puddles, etc.