After not being updated for a few mainline kernel release cycles, the real-time (RT) Linux kernel has been updated against
the Linux 3.0 kernel release.
Thomas Gleixner announced the Linux 3.0-rt1 kernel on
the kernel mailing list yesterday, which integrates the RT patch-set atop the vanilla kernel.
For a verbose update on the state of the real-time Linux kernel, see
this earlier email for a good overview. There's also more information on the real-time kernel via the
Kernel.org Wiki.