PC-BSD 10.0 RC3 came out shortly after the release of FreeBSD 10.0-RC4, which is expected to be the last development release before having the long overdue official release.
Besides riding off the FreeBSD 10.0 packages and its features like AMD Radeon KMS support, PC-BSD 10.0 also has a new text-based installer, ISO hybrid support for writing to USB drives, a UEFI loader on the installation media, and new desktop options. Besides KDE, offered in PC-BSD 10.0 is now GNOME 3, MATE, and Cinnamon.
PC-BSD 10.0 RC3 for this week pulls in the latest upstream FreeBSD 10 changes. As noted in their weekly digest is also improved detection of AMD Hybrid Graphics systems. With the FreeBSD/PC-BSD open-source graphics drivers being ported from the Linux kernel, their hybrid (dual) GPU graphics support isn't any better than Linux, and these improvements is just better detection if trying to load the X Server off the first GPU fails. Improved NVIDIA Hybrid/Optimus support for PC-BSD/FreeBSD support still needs to be investigated.
More details on PC-BSD 10.0 RC3 can be found via the mailing list announcement.