Good news! I just booted 2.6.13-grml with unionfs working. Thanks to Dave Quigley and the other unionfs-guys for their work! That was a very important step for current state of grml. Today (14th of september) we will have a developer meeting in Graz and a new devel-release should be available really soon now. There's only one release-stopper left, that's the new config-framework. People out there: we are coming closer to grml 0.5. :)
I just finished main work on 2.6.13-grml including all the extra modules. Now I'll update documentation on grml.org/kernel-devel/ and will integrate the kernel in chroot of grml 0.4-3. I'm running 2.6.13-grml already on my develmachine, works very fine so far.