From the "little devil" files:

FreeBSD 6.4 is now out and it's likely to be the last release on the 6.x branch of the free operating system. The first FreeBSD 6 release came back in 2005, FreeBSD 6.1 came in 2006 and 6.2 in 2007. The FreeBSD 6.x branch became Legacy (that is not the leading edge of development) when FreeBSD 7.x was released earlier this year.

The FreeBSD 6.4 update looks to me to be a basic point upgrade for key applications. According to the release announcement  the big items are:

* New and much-improved NFS Lock Manager (NLM) client
* Support for the Camellia cipher
* boot loader changes allow, among other things, booting from USB devices and booting from GPT-labeled devices with GPT-enabled BIOSes
 * DVD install ISO images for amd64/i386
 * KDE updated to 3.5.10, GNOME updated to 2.22.3
* Updates for BIND, sendmail, OpenPAM, and others

Even though this is the last point release for FreeBSD 6.x, security support for FreeBSD 6.4 will extend until November 30th 2010. So that means for you FreeBSD 6.x users out there, you've got two years to migrate (if you want to stay relatively current).