If you want to add rounded corners to your iPhone, iPad or iPod, you can do this by and app – RoundCorners.

Round Corners is a cydia app by which one can add rounded corners to these devices.
The size of this app is compressed as 8 Kb and installed as 33 kb.
What basically it does is that it converts the corners of these iDevices into black color. And, it seems to you as rounded corners.

Requirements
* iOS 4.0+
* Window Planer that is compatible with iOS 4.0.

How to turn corners round
* Download this app from BigBoss Cydia Repository
* Install it.
* Reboot your device.