Ricoh/Pentax has announced a firmware for their Pentax K-3 v1.02. You can download it at here

This firmware update allows users to bracket exposures by AA filter simulation mode. As a reminder, the K-3 lacks a physical anti-aliasing filter, but simulates the blurring effect via minute movement of its sensor, with two intensity levels available (three if you include ‘off’). Firmware v1.02 allows you to shoot a burst of sequential images at each AA filter level, to fine-tune the optimal balance between resolution and artifacts like moiré.