I left a comment on the author's website, but thought this might be just as fast to try here.
Love this plugin, really impressed in how it works. The lightbox features work fine in IE and Opera, but when I go to view a photo in Firefox, it downloads the photo to my desktop instead of viewing it in the browser...
Any ideas of what is wrong? I have PHP 5.2.3 installed on the server, using WP 2.3.1, and installed kPicasa 0.0.3.