Surrogate Key vs Natural Key

My friend André Cardoso has just posted a link list about this modeling dilemma.

Though I'm a surrogate key myself, I can't overlook some some natural key advantages. To me, the problem of natural keys is that it is hard to ensure them to be natural - at least over time. Also for normalization and implementation reasons, I adopt surrogate keys to most of my design. Even on N-M tables...