While it doesn't look like Reiser4 will ever be merged into the mainline Linux kernel, work on the file-system continues by the remaining developers. The most recent Reiser4 file-system patch was uploaded this month to its SourceForge page.
Since the previous update in May, Reiser4 has been ported to run on the Linux 3.10 kernel. There's also a fix for incorrect cluster node accounting causing a potential kernel oops with Reiser4's transparent compression support.
Updated Reiser4 benchmarks from Linux 3.10 against the competition is forthcoming on Phoronix while our previous benchmarks were Reiser4 on the Linux 3.5 kernel.