The MultiButton is meant to provide developers with the ability to replicate some of the UI paradigms that are common to the UITableView iOS UI's (for more on UITableView see the presentation below). The MultiButton doesn't include anything radically special, its just a standard Lead Component based UI.
The MultiButton is mostly designed for use with the GUI builder although using it from code is similar. It allows for up to 4 rows of text, an icon and an emblem. It also includes features allowing the first two rows to occupy a single line and to use a CheckBox/Radio button for the emblem element.
A common source of confusion is the difference between the icon and the emblem since both may have an icon image associated with them. The icon is an image representing the entry while the emblem is an optional visual representation of the action that will be undertaken when the element is pressed. Both may be used simultaneously or individually of one another.