The latest version of this mini-HOWTO can be downloaded from this site in several formats (including SGML and PostScript.) The document has been translated into Japanese by Mr. Teruyoshi Fujiwara as part of the JF project.
Gregor Hoffleit maintains a site with information about the developement of U2FS and UFS.
Annelise Anderson is working on a Linux+FreeBSD FAQ, which will cover the same subjects as this mini-HOWTO (and more.) The FAQ is intended to be part of the freebsd-doc project.
You can find some articles about the difference between Linux and FreeBSD here.
You can find more informations about FreeBSD (and download the whole system) at this site. You can also buy the system on CDROMs from Walnut Creek CDROM (their servers are running FreeBSD.)
The Linux Kernel HOWTO (and this mini-HOWTO) is released as part of The Linux Documentation Project.