The Reiser4 patch directory hasn't even been restored since the downing of Kernel.org, but at least their Wiki is back online, which notes the Linux 2.6.38 kernel as the latest. On reiserfs-devel is where some discussions do take place (circa two dozen per month) with some patches for Reiser4.
It's on the Reiser file-system mailing list where Edward Shishkin, the former Namesys employee who has taken over Reiser4 development since the jailing of Hans Reiser, has shared a brief status update.
Reiser4 has had an unknown fate for the past half-decade and it was back in 2009 when Shishkin had told Phoronix Reiser4 might go for mainline inclusion in 2010. Nearly one year ago, in January of 2011, Edward had a new update for Phoronix. In that email, he told me he doesn't see any technical obstacles for including Reiser4 in the mainline Linux kernel, but he doesn't see it happening without any vendor stepping up to support the technically-advanced file-system. In October, he then said pushing Reiser4 into the mainline Linux kernel is not a high priority.
Now into 2012, Edward Shishkin still doesn't care about mainlining the file-system to compete with EXT4 and Btrfs. He's provided a few comments on the mailing list.
He shares that he might update the Reiser4 patch-set for the Linux 3.2 kernel. However, what's restricting this work is that there's many VFS and fs-writeback changes within the recent Linux kernel releases that necessitates changes to Reiser4. With Shishkin not working on Reiser4 full-time but rather just as a hobby and he being the only main developer, work on this ReiserFS successor is quite slow. "fs-writeback has been changed a lot and I don't have a time to adjust reiser4 to every stupid VFS change. Anybody care to? I'll provide the hints.."
In a follow-up email, Shishkin comments on the lack of mainline ambitions for Reiser4.
Merging upstream has mostly marketing/political aspects which would mean additional burden for me personally.
Who cares to merge it with upstream? It might be important for some vendor, who is ready to pay money for reiser4 development.
Perhaps we'll consider possibility of merging, but not now. Now, when I spend my weekends for reiser4, I would prefer to concentrate on scientific aspects of file system development.
So don't look for Reiser4 to appear in the mainline Linux kernel anytime soon... The best you can hope for is the Reiser4 file-system patch-set being updated against the latest Git code and for that to then be pulled into something like the Zen kernel, Liquorix, or another experimental distribution project.