A previous version of this hook/plugin for 3.x allowed the group icons to be sorted in the AdminCP. It was a simple drag and drop if I remember correctly, and would work pretty much like the group legend plugin, in which it allows you to drag and drop the order of the icons to be displayed. So if I have group 1,2,3,4,5,6 I could display them in order 4,5,2,1,6,3 if I wanted to, or whatever order.