The new system installer is described as a modern installer for FreeBSD that's able to take advantage of its more modern features. The pc-sysinstall installer, which is a complete replacement to its earlier installer, is written 100% in shell.
This new FreeBSD 9.0 installer has back-end support for ZFS file-systems (with support for RAIDZ, Mirror/Multiple Device Pool setup), GELI-based encryption, auto-labeling of file-systems using glabel, big disk support using GPT/EFI, and full installation logging.
This new installer has been in the works for a while, but has already been used a bit within the PC-BSD variant. FreeBSD 9.0 is using the text-based back-end rather than an X11 variant.
Sadly, this new FreeBSD installer still isn't quite as usable as the text-based Debian installer or Red Hat's Anaconda. At least pc-sysinstall is a functional improvement over the earlier sysinstall.
Besides the new inseraller, other FreeBSD 9.0 enhancements is an updated version of the ZFS file-system, USB 3.0 support, new device drivers, and further work on building under Clang/LLVM. Due to development delays, the final release of FreeBSD 9.0 is still at least another month out.
For those Linux desktop users that may want to toy around with FreeBSD but are looking for a GUI-based installer and a desktop environment provided by default with easy package management, try out PC-BSD.