When I get a chance, I'll restore the one-line change to the Red and Blue themes' CSS so striping in chatter will once again not be the default for those themes. And I'll post instructions on how to turn on striping in whatever colors you fancy. But the default chatter will have the same old colors, just with a few pixels of vertical space between uterrances (which you can also adjust via CSS). (And I'll restore the highlight colors in those themes to be the original, less-subtle shades.)
That is all (for now).