Differentiating between 'new species' and 'mutation' definitely results in a gray area. I personally don't see the necessity for single generational 'leap' mutations in the framework of evolution. A lot of people have difficulty visualizing and conceptually understanding the magnitudes of time involved in evolution. Isolated ecosystems and gradual mutation together can explain current biodiversity. Proving there were no intermediary stages in evolutionary bounds and leaps is difficult to say the least and I would bet almost all of them can be quickly traced back to
this practice that a lot of IDer's like to ignore.