How to Zoom In on Kindle 3?

1) Click on the Aa button (where you can choose your text size/portrait-landscape mode)

2) Then choose the % you want to zoom into (Fit to Width, 150%, 200%, 300%, Actual Size)

3) Profit!!!

PDF Zoom

Each percentage of zoom brings up a box the size of the zoom level that you can move around the screen to choose where to zoom in. Also, the zoom setting remains when turning pages.