Paul Nelson is a philosopher of biology who gave a talk at Saddleback Church in California the Sunday after Thanksgiving. His topic was on why unguided natural processes, particularly genetic mutation and natural selection, cannot by themselves account for the evolution of microbes to mammals.
As Nelson puts it natural selection is real, but it can only conserve, it cannot create. Nelson explains one of the gravest difficulties for Darwinian evolution as a creative force - the origin of different animal body plans. The difference between a worm and a fly is enormous, but the kinds of mutations in the genomes of any ancestral species that would be needed to create either worms or flies are invariably lethal to the organism.
The video of Nelson's presentation is forty minutes long, but for someone interested in his argument and the ramifications of the evolutionary inadequacy of purely natural processes it only seems like ten minutes. Give it a look here.