A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
What kind of progressive reveal? I think what you want is done with custom animation. If it is text, you can animate the entire text box to come in by first, second, or third level paragraphs. If it is non-text objects, you can set an animation for each one. If it is one big picture that you want to reveal piece by piece, your best bet is probably to cover the picture with rectangles (or other shapes) and assign exit animations to each one.
David Marcovitz
Author of Powerful PowerPoint for Educators