  We present the main results of a numerical study of weak lensing cluster
counting. We examine the scaling with cosmology of the projected-density-peak
mass function. Our main conclusion is that the projected-peak and the
three-dimensional mass functions scale with cosmology in an astonishingly close
way. This means that, despite being derived from a two-dimensional field, the
weak lensing cluster abundance can be used to constrain cosmology in the same
way as the three-dimensional mass function probed by other types of surveys.
