Mathematica 8 introduces interactive content delivered by Wolfram|Alpha directly into your documents. Additionally, Mathematica 8 extends the existing set of interface controls and introduces paradigms for running dynamic computations that are not linked directly to the output of those computations.
MouseAppearance — context-sensitive mouse cursor appearance
Overlay — visually overlay expressions
InputField (modified) — create scrolling input fields, mask input fields, and add ghost contents
DynamicWrapper — display an object that dynamically updates an expression but does not display that expression