GP2XMB is an alternative launcher for the GP2X, with the same visual layout as the Cross Media Bar.

Cross Media Bar officially abbreviated as XMB, is a GUI system developed by Sony. It was originally used in the PSX media center as the user interface. The interface features icons, which are spread horizontally across the screen. Navigation moves the icons, instead of a cursor. These icons are used as categories to organize the options available to the user. When an icon is selected on the horizontal bar, several more appear vertically, above and below it (selectable by the up and down directions on a directional pad). The Cross Media Bar is used as the default interface on both the PlayStation Portable and the PlayStation 3.

Description taken from Wikipedia.