tim7:
Can this technique be used to program an ATmega328 with a non-Uno bootloader?
For example, can I use an Uno board (minus microcontroller chip) as a USB-to-Serial programming interface for something like the Arduino Pro-Mini? (The Pro-Mini board uses the ATmegaBOOT, whilst the Uno uses Optiboot, AFAIK)
I also used this method (empty UNO board to program ATmega328 chip) to program a 328 chip which had the older Duemilanove bootloader on it. The only difference in programming was that I had to choose "Duemilanove and ..." as the board type (even though the actual board was an UNO).
One difference in the bootloaders is that at power-up, the optiboot loaded chip starts the sketch instantly. The Duemilanove-bootloaded chip waits one second. However, both boards wait a second after a reset press, before running the sketch.
I'm not sure what a Pro-Mini is, exactly. But if it doesn't have the USB port, there may be a way to use the UNO to communicate with it. At least the bootloader difference shouldn't be an issue.