If you tried to download the iPhone Facebook sidebar extension or the latest MidnightFox theme beta, you may have noticed the button didn’t properly install the files. Instead it threw some odd error. This is an issue that effects mostly Windows users.
I’ve since been made aware of the issue and included a link to download the theme and extension file directly. Once downloaded, just open your addon’s window in Firefox, drag and drop them in and they should install.
Sorry about the confusion and thanks to those who brought it to my attention.