This is from last November but I hadn't seen it before now.

Recent years have witnessed many proposals for anonymous routing in overlay peer-to-peer networks. To provide both sender and receiver anonymity, the proposed protocols require the overlay nodes to have public-private key pairs, with the public keys known to everyone. In practice, however, key distribution and management are well-known difficult problems that have crippled any widespread deployment of anonymous routing. In this paper, we propose a novel protocol that uses a combination of information slicing and source routing to provide anonymous communication similar to Onion Routing but without a public key infrastructure.