The aim of this work is to present Campus++, a location-based publish-subscribe system for intermittently connected delay tolerant networks, exploiting IEEE 802.15.4 devices, and taking into due account the severe constraints deriving fromtheir physical characteristics. We describe our proposed architectural model and how we implemented our solution in a real test-bed. We investigate the trade-off between reduction of delay and storage requirements when nodes are memory-constrained. We provide some insights in this trade-off and propose simple rules to dimension the number of replicas per topic. To this end, we derive analytical models and we validate them with simulations. We point out that our system can be easily adapted to operate in a fully distributed, infrastructureless way, allowing free communications e.g. in disaster areas or in areas in which "usual" communications means are either non existent or intentionally made unavailable. Copyright 2011 ACM.