  Recent measurements of event-by-event elliptic flow in Au+Au collisions at
sqrt(sNN) = 200 GeV exhibit large relative fluctuations of about 40~50%. The
data are well described by fluctuations in the shape of the initial collision
region, as estimated event-by-event with the participant eccentricity using
Glauber Monte Carlo. These results, combined with the demonstrated participant
eccentricity scaling of the elliptic flow across nuclear species, constitute
evidence of transverse granularity in the initial matter production in these
collisions.
