I recently discovered the Open Hardware Pogo-Pin Programmer project. It uses a header with a set of pogo pins and a single row of eight pads on a PCB in a space of about 400mils by 50mils to provide the connections necessary to program a part in-circuit. It saves a lot of board space compared to the typical approach of using a dual row header with 0.1" pin spacing. In addition to the amount of board space it saves it also eliminates the cost of the dual row header.
I may adopt the use of a pogo pin based programmer connection in future projects. I am considering its use in this project but I don't think it will provide any real benefit so it may not be worth the effort to update the PCB.