I can't see why not( but I'm half blind). I think It's worth a try anyway.
Connect: (Duemilanove to Atmega2560)
SCK to SCK
MISO to MISO
MOSI to MOSI
Pin 10 to Reset
5V to VCC (all)
GND to GND (all)
Also, you will likely have to disable the auto-reset on the Duemilanove. This is apparently usually done by placing a 10uF capacitor from Reset on the Duemilanove to ground.