This is the online version of Orbiter Racing League ( http://www.orbithangar.com/searchid.php?ID=4126 ). It uses OMP (Orbiter Multiplayer Project) as multiplayer framework.
All necessary components are included, with OMP client and server in version 0.6.1 . Please report OMP bugs here: http://orbiter-forum.com/forumdisplay.php?f=45 .Source code included!