... let me recapitulate the possible versions of the linux kernel:

the normal kernel26 release is versioned 2.6.x

if something is broken in the release, we simply add 2.6.x.1 to it and hope people do not realize or do realize but use the new one and are quiet

unfortunately this .1 is the same var, as the var that is the marker for another tree of the kernel sources (mm, ck ...), so if you do not use the vanilla kernel, you are "messing around"