This updates the static icons, giving unique icons for things such as Utsusemi, Bar-spells, Songs, ect. It's very helpful not having 4 or 5 icons that all look the same on your screen.
This is very easy to install. Just backup one .DAT file (rename it .DAT.bak or something) and put the new file in. Be sure to read the directions so you use the .DAT file for the NA version and not the JP version. Enjoy.
You can find updates posted here:http://www.livejournal.com/users/faranim/