  Recent RHIC data show evidence of multiple hadron production mechanisms in
heavy ion collisions compared to simple fragmentation in vacuum. I will review
the measurements of collective flow, high momentum quenching, and two particle
angular correlations to show that neither thermal production nor string
fragmentation can describe the abundances, the angular distributions or the
kinematic properties of all hadrons produced at RHIC. The proposed new
hadronization mechanisms not only serve as evidence for a deconfined partonic
phase of matter, but also for strong coupling of the degrees of freedom in the
deconfined phase. I will point out a surprising lack of flavor dependence in
these properties at RHIC, though, which might have to lead to further revisions
of our understanding of the relevant degrees of freedom in the partonic phase
and during the hadronization process.
