Qi-hardware maintaints a repository following the openwrt stable backfire, having changes that will go into the openwrt. They call this project openwrt-xburst and has changes that go from time to time to openwrt.
The kernel there is 2.6.32.
Openwrt uses a system called feeds, to extend the software beyond the default minimal systems. Qi-harware provides a openwrt-packages feed that can be used additionally to the usual openwrt feeds.
The official image (that a user can build following the instructions) comes from openwrt-xburst + the usual openwrt feeds + openwrt-packages.
I think only openwrt developers run this on the nanonote. Lars maintains the xburst target, with very up to date kernel patches.
Nixpkgs uses the patches there to build the nanonote kernel, based on the vanilla 2.6.35, at the time of writing. I received the recomendation from larsc when I asked for the latest stable kernel.
The Jlime distribution is meant to be used with any kernel of openwrt-trunk, because they allow to have the qi-openwrt distribution and kernel in the NAND, and boot Jlime from SD (pressing M-powerbutton to turn the nanonote on).
Their download page now offers 2.6.34 of 02aug2010 for the NAND.
Larsc uses the qi-kernel project to handle pushing the nanonote kernel patches upstream to the linux kernel. 2.6.36 is the first vanilla kernel that boots fine in the nanonote, although the patches are not all pushed upstream.
The development happens specially in branches, not in master. As larsc is doing this work each branch should be close to what kernel patches are in Openwrt trunk