Some preliminary evidence suggests the conjecture that the collective behaviour of systems having long-range interactions may be described more effectively by the Tsallis rather than by the Boltzmann/Gibbs/Shannon entropy. To this end, we examine consequences of the biggest difference between these two entropies: their composition properties. We rely on a metric formalism that establishes the "hyperbolic" nature of Tsallis entropy and explore some of its consequences for the underlying systems. We present some recent and some forthcoming results of our work

5 pages, No figures. Standard LaTeX2e. Contributed talk to ICNAAM 2013, Rhodes, Greece 21-27 September 2013. To appear in the proceedings