Rare hadronic charmless B-meson decays into final states with a phi or an
eta' are dominated by the b -> s(d) s-bar s gluonic penguins, possibly
with a significant contribution from electroweak penguins, while other
Standard Model contributions are strongly suppressed. Many models of new
physics introduce new heavy particles, with new couplings, that would
contribute to these decays at the loop level, potentially leading to large
deviations of the CP-violating observables from their SM predictions. The
amounts of CP and flavor violation observed in these decays can therefore
be used to constrain the parameter space of models of new physics.

In this talk, I will give a brief overview of the physics of CP violation
(but without going into CP violation in B0-B0bar mixing), describe the
analysis technique, and, finally, present and discuss the most recent
results on these modes from BaBar and Belle.