Whenever you decide to open (or save) a file from within an application, a sheet or dialog box will display. New in 10.5, the icon view push button at the top left of the sheet/dialog box can be held down to give you a menu with the ability to change the Icon Size between 16x16, 32x32, 64x64 or 128x128, and change the Label Position to either Bottom or Right:
Mac OS X Hints
http://hints.macworld.com/article.php?story=20071026232925399