From Final Crisis #5. Written by Grant Morrison, art by J.G. Jones and Alex Sinclair.
It surprised me. I wasn't reading FC when this came out in December, so I don't know if we discussed it on old s_d at the time. I looked around online to see if anybody had really talked about it and then ran across this, too:
From Action Comics #872. Written by Geoff Johns, art by Pete Woods and Brad Anderson.