Failed to Change Carrier-Logo on a jailbreaked iPhone 4 with iOS 5 today, i wanted to change my carrier logo on my iPhone. 
Every Tutorial failed. Even if i complete delete my Carrier-Folder: nothing happens. 
The path on the iPhone: /System/Library/Carrier Bundles/iPhone/TMobile_Germany.bundle 

There isn't any other path were the icons can be. 

I restarted the iPhone many times and changed four times the size and the name of the images.

Any suggestion?
The best suggestion I can give you is downloading Fake Carrier from Cydia. You can change the text, and use emoticons from Emoji as your carrier logo. 

This is the best and probably the easiest way I've found so far.