On a regular basis a "kernel.org Kernel" (or mainline) is released with a name like "Linux 2.6.32". These Kernels are developed by a community of developers and maintained by Linus Torvalds. For more information about this take a look at http://kernel.org.
At the beginning of a openSUSE development cycle the Kernel team takes a released "kernel.org Kernel" and adds a number of patches to increase stability and introduce new features. These patches are kept to a minimum and most all will eventually make it into the kernel.org Kernel. This Kernel is maintained in the Kernel git repository.