How to build FontForge binary packages
Matthew Petroff documents the Windows build process on his site.
Mac OS X
FontForge binary builds for MacOS X 10.7 and 10.8 can be created with MacPorts. By default they will be built with a prefix of /opt/local. This is known to case weird problems for people already having MacPorts installed in /opt/local trying to install that package, because it will overwrite MacPorts-owned files.
For this reason, please refrain from distributing binary packages built from a MacPorts installation with /opt/local as prefix. Instead, install a different MacPorts copy somewhere else (e.g., /opt/fontforge). The guide has information on how to do this, see MacPorts Manual section 2.3.2.