I'd like to create some text and lines with an embossed look to them, as if they were slightly sunken into the object behind them. I have created an icon with a light->dark gradient from top-> bottom and I'd like for the embossing to be as if a light were shining on the icon from up top. I've played w/ the Filters->Color->Color Emboss filter and it hints at what I want to do, but I couldn't understand how it was working to change it to be the way I'd like it.
The calculator icon from the iPhone (linked below) is a very clear example of this: the text, dividing lines and even the icon edges appear sunken and lit from above.
Any suggestions or tips on how to do this? Thanks!

http://img135.imageshack.us/img135/5706/img0113.png