up-to-date: kernel 3.2.54. (Always read current kernel sources!) This topic has maintainer 
rfree
SameKernel is idea to make kernel reproducible (deterministic, verifiable build). So that each time you build given kernel version (with same configuration), using same tools you will get binary identical resulting files.
This task is being now developed as part of Mempo project and documented on https://wiki.debian.org/SameKernel (developed in Debian, how ever results from it will be applicable to all kernel builds).
Please see that page for details and please help our research: group Mempo is looking (2014-01) for hackers to help on this.
Problems (smiley mark what is done)
usage of __LINE__ and __FILE__ can be fixed with a small patch in the remaining places it is used - some settings (like root device?) can be fixed by patch/options
- distribution like Debian can pack the files into a package in non-deterministic way (but Debian newer dpkg does this correctly)
- compilation times could be embbed into binaries - faketime will work around this for now
- gz generation could include times etc - faketime and proper gz options (change to build script) resolves this
compiler and/or linker might add --build-id - it is fixed by adding changing --build-id to --build-id=none in the main Makefile as done by Mempo SameKernel script. See [vmlinux/asm-notes]
Again, to see one way how this problems can be resolved see this sub-project: https://wiki.debian.org/SameKernel
Name "SameKernel" is used by Mempo because the alternatives are harder to spell/remember.