If you are interested in the change itself, it can be found in this commit. The reader and writer usage is fairly straight forward and similar to the JMS JmsItemReader and JmsItemWriter implementations. Example usage of the AMQP version can be found in my rabbitmq-samples git repository under the "batch-amqp-itemreader-writer" module. Until Spring Batch 2.2.0 is released, you will need to clone and install to your local maven repository the master branch of Spring Batch, then remove the comment around the batch-amqp-itemreader-writer module in the rabbitmq-samples main POM and build the samples.
Update: this sample is now deprecated as it has been merged into the Spring Batch samples project as of 2.2.0. See spring-batch-samples/src/test/java/org/springframework/batch/sample/AMQPJobFunctionalTests.java for more details. Thanks to Wayne Lund for taking interest in the sample and merging it in!