Stunt Software - PhotoBooth
I need this software! Too bad it's going to cost me $20, but it's not like there's much competition. I'd hoped Portraits and Prints would do this -- but they missed the boat. (Too bad, it would have been an easy add for them).
Lets one browse the iPhoto library, choose images to print, then crop as needed for printing.
Update 1/05: Portraits & Prints apparently does something similar, but as of 10/04 they didn't ship wtih the right template. I'll have to check back and see if they've bundled the template.