FreeBSD 10.0-RC4 just has tightened default restrictions for the NTPD server and a fix for a kernel crash discovered with a recent Java port update. WIth this expected to be the last release candidate, there isn't much more than that.
Details on FreeBSD 10.0-RC4 can be found via the mailing list announcement. After months of delays, the final release of FreeBSD 10.0 will likely come within a week or two. FreeBSD 10.0 has many new features to hopefully make up for the delays.