It's 2 years since the SD1 was first shown, and 1 1/2 years since a family of Sigma bodies using the 15.4/16Mp sensor began to fill out. There are now thousands of DP and SD Merrill bodies out there, and yet Lightroom/ACR still have no support for them.
Third party support does exist from one small developer, so it can't be that hard to process these files - please, support these cameras or give a definitive explanation for the lack of support so users can pursue the right angle to get support.