Nur zur Info, Atmel sagt in der Appnote dass es geht.
http://www.atmel.com/images/doc2585.pdf

1. Introduction
This application note describes how to setup and use the on-chip Serial Peripheral
Interface (SPI) of the AVR micro-controller. Most AVR devices come with an on board
SPI and can be configured according to this document. After a theoretical background
it will be shown how to configure the SPI
to run in both mast
er mode and slave mode