After the ribosome structures: how does peptidyl transferase work?

Atomic resolution crystal structures of the large subunit published since the middle of August 2000 prove that the peptidyl transferase center of the ribosome, which is the site of peptide-bond formation, is composed entirely of RNA; the ribosome is a ribozyme. They also demonstrate that alignment of the CCA ends of ribosome-bound peptidyl tRNA and aminoacyl tRNA in the peptidyl transferase center contributes significantly to its catalytic power. Several issues remain unresolved. For example, do any components of the site enhance the rate of peptide-bond formation chemically? Do intact ribosomes make peptide bonds the same way as the isolated large subunits that have been the source of all this atomic resolution structural information?