Within posterous when you hover on an image it displays a box enabling the user to download or view the full size image. Here is the example of how this should work.
I am trying to find out why this does not work in the theme I created Here. Any and all help would be greatly appreciated.
I took a quick look at your code. The span that's supposed to show up; 1 has no id associated with it and two is not showing when you hover over the image. Make sure your javsacript is correct. I think it is most likely being referenced wrong.