Phenomenology of high gluon density QCD and heavy-ion physics at ISMD 2011. x smaller than ever!

I provide a brief summary of the theory presentations at ISMD 2011 related to the phenomenology of small-x QCD evolution and its application to particle production and fluctuations in high-energy hadron and heavy-ion collisions. I also mention some challenges for quantitative phenomenology which emerged from the LHC, such as understanding the long-range 'ridge' in high-multiplicity p + p collisions, the transverse momentum distributions in p + p at semi-hard p sub(perpendicular), and the origin and scale of density fluctuations in the initial state of heavy-ion collisions. (author)