From the USA, Dean & Deluca's Doughnut Muffin
The trend over here is for fillings in the centre of everything that can be baked - muffins and cup cakes. See http://bakeitinacake.com/ for inspiration and ideas.
The Cafe business for the professional operator - keeping up to date with what's new and interesting - written by Paul Cottrell, Turpin Smale Catering Consultants