I use Picasa on my laptop to organize personal photo albums that I share with friends, and work photo albums that I use for project photos. I don't need any sort of heavy photo-editing software, so Picasa has worked great as a simple solution to organize my pictures.
However, I would like a separate installation of Picasa for each, corresponding to my separate personal and work Google accounts. This is for a whole list of reasons, for instance I don't want tags to be shared, and I don't want to accidentally open pictures of my friends drunk at a bar when I'm trying to show coworkers how my last engineering project turned out. You get the idea.