It's called long panel because the user panel is allowed to extend beyond the post height, but when I changed the avatar rules, I apparently got rid of the people with the longest user panels. MJ is the only one left, I think. In any case, the purpose is reduction of the minimum post height from 225px to 160px. I got tired of tons of blank space below each post because of every thing that could be in the user panel, so I did somthing about it.

Here's an example of a worst case:
http://zelaron.com/forum/showpost.php?p=607897