  We introduce the notion of distributed quantum dense coding, i.e. the
generalization of quantum dense coding to more than one sender and more than
one receiver. We show that global operations (as compared to local operations)
of the senders do not increase the information transfer capacity, in the case
of a single receiver. For the case of two receivers, using local operations and
classical communication, a non-trivial upper bound for the capacity is derived.
We propose a general classification scheme of quantum states according to their
usefulness for dense coding. In the bipartite case (for any dimensions), bound
entanglement is not useful for this task.
