Today I've released new version of my raw converter for macs.
RPP is a free application representing combined effort of few photographers to make a converter our way. All I ask is some feedback - about color accuracy, conversion quality and so on.
For more details please check my site:
http://www.lexa.ru/andyt/RPP/

It supports practically all DSLRs, most of them have custom profiles and more to go on the next week (Olympus cameras f.e.)

List of cameras with built-in custom profiles:

Canon DSLRs D30, D60, 300D, 350D, 400D, 10D, 20D, 30D, 5D, 1D, 1D MkII, 1D Mk IIn, 1Ds, 1Ds MkII, 1D MkIII

Nikon D1 and all other Nikon DSLRs

Fuji S2-Pro, S3-Pro, S5-Pro

Minolta DSLRs 5D and 7D

Pentax DSLRs *istD, *istDL, *istDL2, *istDS, *istDS2, K10D, K100D, K110D

Leica DMR, M8, Digilux 3

Sony A100, R1

Canon P&S G2, G3, G5, G6, Pro1

Thank you,
Andrey

No Mamiya support - MEF
No Sinar Support - STI

Do you plan to do it?

Short answer is yes.
Long answer - this may take some time. I need those RAW files, so if you or somebody else willing to provide them this would greatly speedup the process and I can roll preliminary support out very soon. Images should be colorful, sharp and with many small details.

Andrey