@OP, here's the post I used to remove the shadows:
This is for iPhone 4 running iOS 4.0.1, Suave Icons. Remove shadows......... This will only look correct if all of your icons are themed.
Remove shadow from App Store icons.
Using your iPhone browser software i.e DiskAid, iPhone Browser....... etc. Navigate to:
system/library/privateframeworks/mobileicons.framework
Rename the following 3 files with a 1 or _alt or anything you want to use at the end of @2x
Example:
AppIconMask@2x_alt.png
AppIconMask@2x.png AppIconOverlay@2x.png AppIconShadow@2x.png
****DO NOT DELETE THESE FILES!!!!! RENAME THEM********
After a respring, you will notice that your App Store icons will look wierd. This will break the auto theming that the OS does automatically for App Store apps that doesnt have pre-made icons. So if all of your App Store icons are not themed, they are going to look wierd until you theme them. I do know that there are other ways of doing this by replacing the masks but I find this to look the cleanest.