avrdude version 5.4 has just been released.
Here is the list of major changes, compared to 5.3.1:
* New devices supported:
- AT90PWM2B/AT90PWM3B
* Bugfixes.
* Source code rearranged so that the functionality is now built
into a libavrdude.a library where main.c is currently the only
existing frontend.
* Implement ATmega256x support for butterfly/avr109.