The human genome has more than 40 kinesin genes whose protein products organize intracellular traffic along microtubules. Research during the past two years has begun to elucidate the cargoes carried by kinesins and the nature of the kinesin-cargo linkage. Modular protein-protein interactions connect kinesins to diverse cellular molecules, which, apart from their other functions, serve as kinesin-cargo linkers. Many of these newly identified linkers are scaffolds for signaling pathways, and mounting evidence now indicates that kinesins transport pre-assembled signaling modules as vesicular cargo. These findings bring together two fields, signal transduction and molecular motors, and lead to a deeper understanding of the interplay between trafficking, localization and intercellular communication.