Gravitational lensing has long been recognized as a powerful  tool for mapping the distribution of dark matter in clusters, and  yet until recently, it has only been applied routinely to individual  clusters. However both strong and weak lensing are developing  rapidly into tools that can routinely be applied to samples  rivaling, for example, those considered by X-ray-only scaling  relation studies.

The Local Cluster Substructure Survey  (LoCuSS) is assembling a sample of ~100 z~0.2 clusters with  HST, Subaru, Chandra, XMM and Sunyaev Zel'dovich Effect  data. The overall goal is to study how the recent assembly  history of the clusters (as revealed by lensing-based mass  maps)  influences the baryons trapped in the clusters, and  calibrate the cluster mass scaling relations (weak lensing, X-ray,  SZ) that will be used for ongoing and future dark energy surveys. 

I will also introduce the multi-wavelength campaign comprising  large programs with GALEX, Subaru, UKIRT, Spitzer and    Herschel to obtain panoramic UV-FIR imaging of 32 clusters with  the aim of witnessing the transformation of infalling spirals.