Revision 3 will swap connections of PD6 and PD7 in order to enable even more functions of the MCU.
(It is possible to use the internal analogous comperator module)
If you experiencing instabilities during operation (ATmega8A, ATmega328p?) put some capacitor with 0.1uF or more somewhere near the microcontroller between Vcc and GND. (For example between PIN 7 and PIN 8)
Other default- and bootloader firmwares only are provided for revision 3.
Most of them are still inofficial and need further testing.
If not noted otherwise, example binaries/hexfiles are always compiled for ATmega8.