One use case for fork()--which is used extensively on Android--is to build an expensive template process that can then be replicated for later work, which is exactly what people often want for the behavior with virtual machines. I wrote an article on the history of linking and loading optimizations leading up to how Android handles their "zygote" which touches on this behavior.

http://www.cydiasubstrate.com/id/727f62ed-69d3-4956-86b2-bc0...