Pretty rich advice from Atmel considering where they put the Xtal pins!!
Surely a better design would have been between nice solid DC lines, where capacitive coupling would be virtually eliminated (possibly a very tiny amount due to ripple or noise on the DC lines). Maybe between Vcc and Gnd, or less frequently switched input like Reset and Gnd?
Siting the low impedance Xtal pin right next to RX0 on the 1284 wasn't very bright was it?
