The Primary palette for the CC button reveals that it is a "Creative Commons License", and indicates the currently selected license textually. The secondary palette contains toggle buttons which can be turned on/off to set the license. The textual license description updates dynamically as these buttons are toggled.
If wanted, additional licenses can be supported. Also, a link to creative commons is included in the palette for more information. (This isn't possible yet, but will be supported in later versions of Sugar.)