I was mulling this over last night as I was going to sleep. It seems
to me that the port maintainer could be relied upon to build the
package for his respective port(s). That way, MacPorts doesn't need to
hunt for a build machine.

Although, someone would need to step up and maintain a cross compiler
port for the maintainers. That would make it easier for the port
maintainers to build the packages. If they could do something like
`port package +g4 +g5 +intel`, I'm sure the idea would go over a lot
better.

Of course, there would then need to be functionality built into port
to pull down binary packages instead of source packages.