Starting from GP 2.0.9, we host the source code of 2.0.X branch in Subversion repository on Google Code project hosting. Development instructions have been updated correspondingly.
GanttProject 2.1 will remain in CVS on SourceForge for a while, but the plan is to migrate it eventually to Google Code.
We're also moving bug tracking to Google Code, but this process is in the very beginning. Feel free to use our bug and feature trackers on SourceForge until the migration is completed.
GanttProject 2.0.9 distributions are available for download from Google Code, as well as from SourceForge