From the announcement, the most important changes between -RC1 and -RC2 are:
- Fix a boot issue caused by some GPT partitioning tools.
- Fix a regression that caused some PCI disk controllers disappearing during boot.
- Fix the FTP path used to fetch distribution packages when installing from the bootonly.iso.
- Fix a regression in sendmail that caused problems between the resolver and Microsoft DNS servers with AAAA lookups.
- Disable MSIs with Adaptec 2230S and 2820SA (aac(4)).
- Update FTP mirror list used by bsdinstall(8) and bsdconfig(8).
- Fix panics caused by early interrupts in igb(4).
- Fix panics when downing or unloading the mlx(4) driver.
You can check out the announcement for update instructions and download locations.
Following this RC release, the PC-BSD project announced PC-BSD 9.2-RC2. Yes, as you will have guessed, it is based on FreeBSD 9.2-RC2.
As always, BETA and RC versions should only be used for testing and evaluation purposes, and never in production!