I got a atmega644p recently (though for the money I should have gotten a 1284p but whatever I know now) thinking that cores were available, popping over to the sanguino site I am greeted with the excellent news that the core files have been brought up to version 0.18.
I like .18, I use it a lot for tight memory situations, but I would like to have a core file for 1.0 as well depending on what mood I am in. Googling around I found the mighty core http://maniacbug.wordpress.com/2011/11/27/arduino-on-atmega1284p-4/
but I have not had the chance to play with it yet, SO what are your experiences and suggestions for 644/1284 core files for 1.0
bootloader is not needed, just core files if that weighs in ...