[Renaud]

The 'Camera+' and '645 Pro' apps are able to save to uncompressed TIFF instead of JPG. They also give you a bit more control over exposure.

Not really RAW, but at least you get all the bits you can.

[prewett]

8-bit TIFF or 16-bit TIFF? If it's 8-bit, then the only benefit you get from TIFF is lack of JPEG artifacts and is identical to JPEG from a JPEG vs. Raw standpoint.