Lipid microdomains within cell membranes are detected by a variety of experimental techniques, each of which characterizes microdomains on a different time and spatial scale. The sum of the data on lipid microdomains has yet to be integrated into a single model of cell membrane structure. Indeed, one highlight of the past year is a new analysis of experimental results which yields a model of a cell membrane which need not contain any microdomains. Other highlights are an estimate of the number of phospholipid molecules in a membrane microdomain and the detection of domain formation in cell membranes in real time. Some progress has also been made in visualizing lipid microdomains within cell membranes. We still await, however, a new model of membrane structure that integrates all experimental results.