"According to the French federation, while international grand master Sebastien Feller, 19, was involved in a game, Cyril Marzolo followed developments over the internet and used computer software to establish the best next move. The answer was then sent by means of a coded text message to the third member of the team, Arnaud Hauchard. The third member would then sit himself at a particular table in the competition hall. Each table represented an agreed square on the chess board."
Feller's prize for these intricate shennanigans? 5,000 Euro, according this report.
Well done, lads!