Pictured here Migatobonito Edward P Scissorhands Owned and showed by Eileen O'Dwyer Copyright (Bob Fox Photos)
Polydactyl simply means extra toes. Historically 40% of foundation maine coons had extra toes, but it is now rare and makes up a small fraction of the maine coon population. Most cat breeders are avid show goers and poly maine coons are only allowed to be shown in Championship class in New Zealand. The UK GCCF views the poly outside the standard of points with 'toes carried close, 5 in front 4 behind'. In TICA they can be shown in the New Traits section.
Poly kittens can have extra toes on the front or back or both. Gina Wild below has extra on the front whereas Blizzard and Avalanche have mittens on the front and extra toes on the back.