Custom calligraphy, by the looks of it.

Typefaces with a similar feel (to name only a few):
http://www.myfonts.com/fonts/mawns/brannboll-ny/
http://www.myfonts.com/fonts/comicraft/spills/
http://www.myfonts.com/fonts/schizotype/ollie/
http://www.myfonts.com/fonts/fenotype/no.-seven/
http://www.myfonts.com/fonts/yes-please/delicious-pro/
http://www.myfonts.com/fonts/flat-it/machiarge/
http://www.myfonts.com/fonts/alphabetsoup/metroscript/