Segue um concorrente Open Source para o MS Project.
OpenProj - Project Management
Linux (deb e rpm), Windows e Mac OS
Descrição tirada do Source Forge
OpenProj by Projity is a desktop replacement of Microsoft Project. OpenProj has equivalent functionality, a familiar user interface and even opens existing MSProject files. OpenProj is interoperable with Project, with a Gantt Chart and PERT chart etc.