I was happy to find your plug-in because it sounds like what I've been looking for. However, when I installed and configured my widget, it does not display.
When I input the RSS url for an album, it correctly updates with my username & album ID, but it also puts "en_US" in the authentication field. I'm guessing this is wrong? My assumption is that the auth field is only required for private albums.
Regardless of whether that field is input or not - no photos display in my sidebar after updating. The title I gave the widget ("Testing") appears, but nothing after it.
The page source looks like this:
<li id="picasa_json-2" class="widget widget_picasa_json"><h2 class="widgettitle">Testing</h2> <ul class="thumbs"></ul></li>