5-Row Keyboard is a new add-on to iPhone that is part of the project iKeyEx. It allows users to use a new 5 lines keyboard, where there are numbers in addition to the letters. Clicking the 123 button will display all the additional symbols.
To see the keyboard you must click on the globe. If the keyboard does not appear, you must activate it via the Settings > General > Keyboards > International Keyboards > 5 Row QWERTY.
This keyboard as avaliable in Cydia for jailbroken iPhones.