FreeBSD 7.2 mostly includes functionality updates and a few bug fixes, although there's a handful of new features baked inside too, such as improved memory management with superpages.
The OS's virtual memory subsystem now supports fully transparent use of superpages for application memory (although the feature is disabled by default). An application's memory pages will now be automatically switched between normal and superpages without any modification to code.
According to FreeBSD's release notes:
This change offers the benefit of large page sizes such as improved virtual memory efficiency and reduced TLB (translation lookaside buffer) misses without downsides like application chnages and virtual memory inflexibility.
Other changes include improvements to the boot loader as well as the kernel's addressable virtual memory space getting bumped to 6GB so subsystems can use more memory. The OS also now supports the UltraSPARC II processor family.
As with previous 7.x releases, version 7.2 retains the ZFS v6 code, with ZFS v13 arriving later in FreeBSD 8.0.
On the desktop corner, FreeBSD has been updated to Gnome 2.26 and KDE 4.2.2. That's the first time FreeBSD has included version 4.x of KDE — although the latest desktop flavor of the OS, PC-BSD 7.1, has been rocking KDE 4.2.2 since April.