I think that rumor got new life a few weeks ago when Anderson announced that just in case of a merger, all non-contract employees at Delta would be protected.

Personally, I don't see such a merger likely any time soon. Delta fought hard to be a "stand alone" airline when US Air tried to take them over, so I doubt they would sell out now.

An interesting tidbit if such a merger were to happen, though: NWA is the only remaining US airline to have "fifth freedom" rights (used to be NWA and Pan Am). That means they can have a base in another country (Japan, Narita base) and conduct international operations from there. Because of this, and NWA being grandfathered in with this, it's unlikely that Delta would take over NWA. The opposite is more likely.