Hi JJ,
You'll probably want to wait for confirmation from one of the official E-Junkie gurus on this one, but I am fairly certain that FaceBook works like MySpace and other such sites which allow you to use html code, but do not allow the use of javascript. For the E-Junkie cart to work in the slick "pop-up" style that you see in the demo, you need the javascript.
Unfortunately, this means that for FaceBook (and other sites like MySpace that do not allow javascript) the E-Junkie cart can only work as a redirection to the shopping cart's own page, and not as the cool "pop-up" that needs javascript.
That being said, being able to use sites like FaceBook and MySpace to promote your products is great, and being able to use the E-Junkie cart to do it is even better. :-)
Take care,
Andrew
Easy E-Junkie
http://www.EasyE-Junkie.com