Open Source Corona Puzzle Game. Description from the page:
This sample code is a demonstration of how you could implement a simple jigsaw puzzle concept using the Corona SDK’s bitmap masking functionality.
I created this a long time ago and it was just sitting on my harddrive, so I thought I’d put it to good use and share it with the developer community.
It is optimized for Galaxy Tab/Nook dimensions, but could of course be tweaked to match any dimensions. It’s the logic you care about anyway!
Download to learn from it, or use the code in your own projects.