  We show that, in a holographic or gauge-gravity approach to the study of the
Quark-Gluon Plasma, the specific entropy density of the plasma produced in a
peripheral heavy-ion collision can be strongly suppressed relative to its value
for central collisions at the same impact energy; this is connected with the
strong vorticity fields which are now known to characterize the peripheral
case. This implies, within the holographic model, that the shear viscosity of
`peripheral plasmas' may be considerably lower than that of the corresponding
`central plasmas', with potentially important consequences for other aspects of
QGP physics, such as the centrality dependence of jet quenching.
