The p-value is one of those important concept in statistics that we all get mixed up (unless you are a statistician I guess). ScienceNow (from AAAS) did an interview with Victor De Gruttola, chair of biostatistics at the Harvard School of Public Health, talking about what the p-value is, how to think about it and how to use it. The interview is the result of a discussion on the results of an AIDS vaccine trial, but the implications of the p-value cover most science.