It's just self-explanatory. A simple texture mod. Probably a beta version of Grove Street.
Proof? Well, CJ sometimes says to his enemies "Orange Grove, motherf*cker!" and other... crap.
INSTALLATION
Either drag the "Orange Grove" file in the Modloader folder (recommended), or replace the .txd files in the gta3.img. (opening it with IMG Factory, or IMG Tool or... whatever.)