The Pushpin Computing project demonstrates several concepts in distributed, embedded, and ubiquitous computing and dense sensor networks. Small pushpin-sized computers, each with two pins resembling thumbtacks, draw their power from a layered polyurethane/aluminum composite into which they are pushed. Communication between pushpins is local and neighbor-to-neighbor via IR. Current work with the Pushpin testbed includes distributed algorithm prototyping, building middleware to allow users to interface with the network, and integrating the Pushpins into a wider, more heterogeneous sensor network.