Chris, here are some resources:
The great evolution website at Berkeley has an easy-to-read section on why evolution is relevant that includes a few pages about medicine.
Five Reasons Why Evolution Is Important, by Steven Newton, NCSE.
- H1N1 & Emerging Diseases
- Antibiotic Resistance
- Drug Development
Evolution: medicine’s most basic science, R.M. Nesse, The Lancet, Volume 372, Pages S21 - S27, 1 December 2008.
Oh, and references therein...