UITextField subclass with placeholders that change into floating labels when the field is populated with text.
Credits for the concept to Matt D. Smith, and his original design:
http://dribbble.com/shots/1254439--GIF-Mobile-Form-Interaction?list=users
JQuery / Zepto.js - Achmad Mahardi
Xamarin.iOS - Greg Shackles
Added a port? Let me know - @jverdi