A company has successfully ported Android 4.4 to PowerPC. Don't know if its open source, or if will run on older Powermacs. They seem to be in the dedicated POWER embeded space, ie PowerPC chips that go in airplanes, space rovers and the like. Running Android on a Powermac would be pretty cool though....
http://biz.einfochips.com/portingan...owerPCWP&utm_medium=social&utm_source=Youtube
http://biz.einfochips.com/portingan...owerPCWP&utm_medium=social&utm_source=Youtube