  Over the past five years, PHOBOS has collected data on proton-proton,
deuteron-gold, Au+Au and Cu+Cu collisions, covering a wide range of collision
energy, collision centrality and system size. Using these data, we have
identified scaling features that are common for all types of high-energy
collisions, as well as collective effects that are unique to the conditions
created in collisions of relativistic nuclei. In this paper, we will focus on
recent results obtained for collisions of Cu nuclei. Both in terms of universal
features of particle production, and in the development of truly collective
effects, the results for Cu nuclei confirm and extend our present understanding
of nuclear collisions at the highest energies. In addition, we will describe
recent unique results on multiplicity fluctuations and particle production at
very low transverse momenta.
