Facebook has given a whole new context to social networking, and made real the concepts of pseudo physical interaction. I mean when (in a non-facebook context) did you last poke someone? In the same way that text messaging allowed the user to flirt with anyone in his/her address book, Facebooks' Poke (and latterly SuperPoke) has satisfied a social demand for people to socially interact without being there. One step closer than email, one step further behind the telephone.
Favour bank hopes to emulate some of those emotive opportunities by giving the users the ability to help each other out. Time will tell if people use it.