Someone claiming to have been to Northwest Airline's Headquarters in Atlanta
mentioned seeing a new livery for the airline. (S)he described it as still red, white and dark blue, but with a wavy design on the tail and engine cowlings.
I believe the poster got Northwest and Delta mixed up as DL's HDQ is in ATL and DL debuted their new design which resembled the poster's description. The person never did, luckily, claim (s)he was intelligent.