Saw this today (21st) in the Argyle Street, Glasgow store. Only took note of it as I know a Mario-mad collector who is always looking out for unusual Mario items. Think they might be a World Cup promo?
I didn't take a picture in the store but I found a few online pictures, added in the next post.
Edit: Added pictures today (22nd) on post #23: http://www.hotukdeals.com/deals/super-mario-football-keychain-figures-1-poundworld-1958406?page=2#post22357708
Looks like it's Mario, Luigi, Yoshi, Donkey Kong and Princess figures available, wearing different teams' strips.