I'm slowly working away at this upcoming TR, but also have most of the pictures on Picasa so this thread was of particular interest.

One method I've found that seems to work is to right-click on the "next image" arrow and just select "copy link target". This might require going back two images from where you want to be, since the right-click itself will actually move the image one over, but I've tested it out on a couple and they have worked so far.

This Image in particular.