Evening,
ManiacBug, I've been ill for the past few months so not been messing with the 1284p and prior to that I was finishing the project I was working on.
I've just setup Arudino 1.0 and changed my project to work and whilst setting everything up I decided to get the 1284p working again. I plugged in my board which I designed as per the beginning of this thread and which worked under 0.22 the program is still on the board and it started flashing away as it should.
I downloaded the zip file from your site as I wanted to get it going with v 1.0 and re-started Arduino. The board appears under the list and I loaded my original 1284p test program (my board has 8 leds and the program flashes all 8 in various sequences).
When I click upload though it compiles correctly but then I get the error:
avrdude: stk500_getsync(): not in sync: resp=0x00