The Economist reviews Odlyzko's piece (PDF) about price discrimination and the Net. The theory's cool, but both seem to miss the fact that current attempts at price discrimination aren't just not working - they're actually massively backfiring.
In fact, the Net - the same mechanism that enables price discrimination - also enables grey markets to thrive, where the differences in price get arbitraged away for profit. This is exactly what students are doing with textbooks, and sick people with drugs.