Kevin Rye has been working on his GPS clock project and wrote a detailed explanation on his blog describing the build:
The great thing about setting the time and date via GPS is that I won’t have to put any buttons on the clock. It’ll set itself, and appear to be completely autonomous. By removing the buttons needed for entering menus and setting the time and date, I can hopefully make the clock that much smaller. Ideally, I don’t want it to be any bigger than the display itself. In addition, shaving a half inch or so off the PCB should save a few bucks when it comes to getting the PCB made.