Multi Theft Auto Codename Blue is in progress and it looks like it will be awesome. It will now be fully integrated into Vice City so will feature almost everything from the single player mode.
Everything will run much smoother and faster.
Much more stable than previous versions.
It's fully moddable
The official website is located at http://www.multitheftauto.com/blue.php so check it out for more in-depth info.
Thanks to Cam for notifying me of this.