For those who would like to custom your dock icon, you can add awesome true iPhone dock icon on your iPhone using "Schiller's iPhone Dock" application through Cydia. It's mean, turn or custom your four or five dock icon looks like true iPhone for your dock icon. See at the screenshot below. It's look great!

Install Schiller's iPhone Dock Via Cydia

Launch Cydia > Select “Sections” at haptic menu > Select “Themes” category > and select “Schiller's iPhone Dock” or you can tap “Search” in Cydia and type “Schiller's iPhone Dock” > Select “install” button at the right top and confirm it to install.

Activate Schiller's iPhone Dock Theme Via WinterBoard

Your Schiller's iPhone Dock is still in the “unactive” condition. That's why your still can't see any changes to your four or five dock icon. To activate it, just launch Winterboard and it does two option on your WinterBoard. Select “Schiller's iPhone Dock”. Your WinterBoard will verify with mark symbol. Press "Home" button and you’ll then bring back to the locked screen. Unlock it and you’ll see a fresh new look of your iPhone.