It seems that Sigma has encrypted the raw data. This will be my first and last Sigma camera. What a pity, because the small Sigma DP2 with the APS sensor delivers an excellent image quality.
Discussion about Sigma DP2 raw file format:
http://www.flickr.com/groups/sigma-dp2/discuss/72157624462103697/Anyway, the latest release of Lightroom seems to work, also the color profile from Colorchecker Passport works.