On march 28th ReGeX and Koolio, regulars members on many GTA related websites announced the release of Vice City Online.
Below is their description of Vice City online:
VCO (Vice City Online) has been created to enable an online multi-player experience for the PC version of the single-player game Grand Theft Auto: Vice City (the 4th installment of the award winning Grand Theft Auto series, created by top game developers Rockstar North).
VCO is a personal project founded by two friends - Justin (ReGeX) and Josh (Koolio). Both are experienced C++ programmers whose shared interests in this cult-game provide the inspiration for this grand adventure. Development on VCO began in October, 2007
You can get more information about the project here