The graphical model I posted yesterday for the GALEX Photon Catalog is, in fact, wrong. I worked on it more today, and will post a better version as soon as I start to really understand Schiminovich's comments about the part of the PSF that comes from the electronics: The reason that GALEX has a broad PSF is in part electronic!
In other but conceptually related news, NYU graduate student Yike Tang (who started working with me recently) has been able to show that building a joint hierarchical model of galaxy shapes and the weak-lensing shear map permits much higher precision (or much higher spatial resolution) shear maps than what you get by doing averaging of galaxy shapes. This idea has been kicking around for a while but I think (and, despite my open-science polemics, hope) that we are the first to actually do it. Much debugging remains, and we are very far from having a paper, but we may just have made LSST and Euclid and DES much more powerful at fixed cost!