ALEXA Mini's software SUP 4.0 has enabled in-camera ARRIRAW recording as a *.mxf-wrapped file. That's a new style of ARRIRAW - but still uncompressed and unencrypted. The big difference is the wrapper: MXF/ARRIRAW is single ARRIRAW frames within a MXF container.
By 4/2016 there are only three tools out now supporting MXF/ARRIRAW:
ARRIRAW Converter - ARRI's free reference tool for ARRIRAW processing