The FreeBSD development community seems to be thriving with the certainty that people now want choice and the more orthodox approach towards Operating Systems seems to be vanishing (latest Linux release being a proof of that). 

FreeBSD has released the FreeBSD Release Engineering paper detailing the different phases of the release engineering process leading up to the actual system build as well as the actual build process and very important discussion on the future directions of development.

The official paper describes:

This paper describes the approach used by the FreeBSD release engineering team to make production quality releases of the FreeBSD Operating System. It details the methodology used for the official FreeBSD releases and describes the tools available for those interested in producing customized FreeBSD releases for corporate rollouts or commercial product-ization.

Read the full paper here