Damn! Fatboy Slim beat me to it... I was about to start that thread meself. Happened to see it too, in the standard Airbus "rainbow" livery, on short final to r/w 33 at 1315Z. Must obviously have been for demo purposes for a prospective client - as mentioned, MYT Lite and DUO would be prime suspects - unless it was some sort of pre-line-training flight for Air France's benefit.
Info, anyone?