There are two Like button implementations: XFBML and Iframe. The XFBML (also available in HTML5-compliant markup) version is more versatile, but requires use of the JavaScript SDK. The XFBML dynamically re-sizes its height according to whether there are profile pictures to display, gives you the ability (through the Javascript library) to listen for like events so that you know in real time when a user clicks the Like button, and it always gives the user the ability to add an optional comment to the like. If users do add a comment, the story published back to Facebook is given more prominence.

public enum FacebookRenderMode

Public Enumeration FacebookRenderMode