the fact that the Whitehead chaps haven't produced an RNA replicator in a test tube yet does not really chip away at the notion of a pre-biotic RNA world. If they did succeed, that does not mean it happened that way. It'll be interesting to say the least when one of those guys produces a self-replicating form of RNA though...
That depends on what you mean when you describe RNA as self-replicating.
In this study, the Bartel lab scientists took the approach again of making 1000 trillion random RNAs go through test-tube evolution to find those that could catalyze RNA formation. After successive rounds of testing, the lab isolated a ribozyme that didn't depend on a particular template sequence, but could build a complementary strand of RNA using information from any general RNA template. In fact, the ribozyme isn't hindered by longer RNA templates and works nearly as well with longer sequences as with shorter ones.
This suggests that if efficiency is increased, it may be possible to replicate the entire ribozyme. The ribozyme also accurately matches bases -- A to U, and C to G -- to the RNA template more than 95 percent of the time, better than any previously isolated ribozyme.