Ok so i was scratching my head for a fair while as to why my grooveshark app from cydia wasnt theming even though i was naming the folder and icon correctly "com.grooveshark.Grooveshark\[email protected]"

Turns out theres a mistake... I checked the info.plist file, and the second mention of this has "com.groovesharky.Grooveshark" Im fairly certain that the y on the first grooveshark was an accident, so I removed it, and voila icon themed!

hope this helps someone