I have just discovered his app, and are really impressed, but would like to know if its portable to a linux client.
If so, we are working on a project that we could use this app, and would help on its development (if the project is approved)
At this point in time, the app is Windows centric, it makes heavy use of MFC and a 3rd party toolkit that is only available for Windows. I wouldn't be surprised to see it migrate away from being Windows centric over time, though.
Have a look at Ganttproject (see http://ganttproject.sourceforge.net\). It's also an opensource project, but this one is written in Java and has no dependancies on the platform or on closed source libraries...
If the linux project begin someday, I think it could interesting to work on a OSX or X11 version for the mac user.
There is no good free planning apprlication on OSX and OWB could be the solution for all the mac users.