  It is by now well known that the relativistic heavy-ion collisions at RHIC,
BNL have produced a strongly interacting fluid with remarkable properties,
among them the lowest ever observed ratio of the coefficient of shear viscosity
to entropy density. Arguments based on ideas from the String Theory, in
particular the AdS/CFT correspondence, led to the conjecture --- now known to
be violated --- that there is an absolute lower limit $1/4 \pi$ on the value of
this ratio. Causal viscous hydrodynamics calculations together with the RHIC
data have put an upper limit on this ratio, a small multiple of $1/4 \pi$, in
the relevant temperature regime. Less well-determined is the ratio of the
coefficient of bulk viscosity to entropy density. These transport coefficients
have also been studied nonperturbatively in the lattice QCD framework, and
perturbatively in the limit of high-temperature QCD. Another interesting
transport coefficient is the coefficient of diffusion which is also being
studied in this context. I review some of these recent developments and then
discuss the opportunities presented by the anticipated LHC data, for the
general nuclear physics audience.
