Update: Subblue has contributed some newer build instructions. These are located in the 'Build - Mac OS X' directory in the source distribution.
First install Qt Open Source for Mac (version 4.5.0 or later).
Now check out the source (see the Linux build instructions), and type the following:
qmake -project -after "CONFIG += opengl"
qmake -spec macx-xcode
Now an XCode project file has been created (mac.xcodeproj - actually a dir).
Open this file in XCode.
Open the 'mac' project, go to "External Frameworks and Libraries" and add QtScript.framework, QtOpenGL.framework and QtXml.framework by browsing to their locations. The header files now need to be added: go to 'Project | Edit Active Target 'mac'' and go to the Build tab. Add the following header search paths:
It should now be possible to compile and run Fragmentarium from XCode.