The AVR is working in the Diavolino. It’s not working in the breadboard. It’s hard to tell exactly what’s not working, except that when I remove it from the board, and place it into the circuit on the breadboard, which I think is correct, it isn’t blinking the LED.
I suspect a clock issue just because it’s one of few problems I can come up with that could cause the chip not to do anything. The other ones being power (and I think it’s getting power ok) and a low reset signal (which I’ve pulled high quite purposefully)… I might be missing something else I’m not thinking of, of course.