This project has intrigued me for a long time. I seriously believe it could eventually become the premiere BSD-flavor OS. Although given all the low-level changes they've made it may not be easy to "label" it BSD in the future.
http://www.dragonflybsd.org/docs/howtos/howtonewkerneldevelo...
"While DragonFly was forked off FreeBSD and has generally quite a few similarities to other *BSD, you definitely cannot rely on understanding FreeBSD to understand what's going on here."