Virtual drug design?

To what extent does computational chemistry actually guide drug design?

This came up in the previous post concerning "virtual screening" of candidate molecules for organic photovoltaics.

Seth Olsen brought to my attention a nice article, Virtual Screening: an endless staircase, by Gisbert Schneider that appeared earlier this year in Nature Reviews Drug Discovery. Here is part of the abstract:

Computational chemistry — in particular, virtual screening — can provide valuable contributions in hit- and lead-compound discovery. Numerous software tools have been developed for this purpose. However, despite the applicability of virtual screening technology being well established, it seems that there are relatively few examples of drug discovery projects in which virtual screening has been the key contributor.

Furthermore, the article says:

Substantial progress in virtual screening requires a profound understanding of the forces that govern protein folding and the dynamics of macromolecular complex formation.

The figure above is taken from a this paper about the action of aspirin.