The recently revised cosmological constraints from the Five-Year WMAP data ameliorate previous tension between cosmological constraints from the microwave background and from cluster abundances .
We demonstrate that the revised estimates of cosmological parameters are in excellent agreement with the mass function of X-ray clusters in the Sloan Digital Sky Survey .
Velocity segregation between galaxies and the underlying dark matter could cause virial mass estimates to be biased , causing the mass scale of the mass function to be offset from the true value .
Modest velocity segregation ( \sigma _ { gxy } / \sigma _ { DM } =1.13 ^ { +0.06 } _ { -0.05 } ) is sufficient to match the mass function to the Five-Year WMAP results .
When the new WMAP results are combined with constraints from supernovae and baryon acoustic oscillations , there is no need for velocity segregation ( \sigma _ { gxy } / \sigma _ { DM } =1.05 \pm 0.05 ) .
This result agrees with expectations for velocity segregation from state-of-the-art numerical simulations of clusters .
Together with the improved agreement between the new WMAP results and recent cosmic shear measurements , this result demonstrates that the amplitude of large-scale structure in the nearby universe matches that predicted from the structure seen in the microwave background .
The new constraint we place on velocity segregation in clusters indicates that virial mass estimates for clusters are reasonably accurate .
This result suggests that future cluster surveys will be able to probe both cosmological parameters and fundamental cluster physics .