In 2004, Google bought Picasa which became their desktop based photo management software. Philipp Lenssen has screenshots of a button that was visible on the Picasa homepage which read, "New! Picasa Web Albums." Since then the button has been removed. However, it did link to a dead page at picasaweb.google.com. If that is a clue to go by, web based Picasa should not be too far.