Ah, the "paged_write" fun that nobody else has a problem with 
This seems to be an issue when low voltage serial programmers try to put Optiboot on. You should be able to eventually get "Blink" onto the 1284p, but any larger sketches will fail.
Try bootloading the "Orginal Mighty 1284" onto the chip and then try to upload any sketch on it. It might fail.
If you bootload/sketch upload this one on the 1284p UART1 (as opposed to UART0) it seems to work well.
http://code.google.com/p/optiboot/downloads/detail?name=optiboot_atmega1284p-u1.hex&can=2&q=
Just replace the "U1" optiboot in the folder of the Mighty1284 Optiboot and burn bootloader.
The history is here: http://arduino.cc/forum/index.php/topic,80483.465.html