I have an avr910-compatible USB programmer that works fine with m128 parts.
I tried to get it to work with an ATmega168 and discovered that avrdude doesn't know the part. The avr910 ID is commented out in my avrdude.conf file.
Somehow, even uisp doesn't know the part!
I eventualy 'hacked' the avrconf file by using an ID that was marked as 'unknown' and it works; I managed to program the fuses, and to program the part.. But it's quite slow (compared to the m128).
Does anyone know the status of the support for these parts ?