I was going to give a concise definition of the Anthropic Principle, but after reading the article, I now feel less than qualified. Here's the definition in Wikipedia.
Smolin begins the debate by claiming that the Anthropic Principle is not falsifiable, and that it does not add anything to existing arguments about the nature of our environment.
I haven't read the entire thing yet, so I haven't chosen sides. However, I found Lee Smolin's comment about the use of the Anthropic principle intriguing:
In the paper I show that every use of the anthropic principle claimed in physics and cosmology is either an example of this fallacy, or is so vague that one can get any conclusion one wants, and match any observation, by manipulating the assumptions made.