CMS just published the rule last week (
here is the Overview ). You can't start Stage 2 until calendar year 2014, but (surprise) it seems like you only need to attest for 3 months for the first year of Stage 2, not a full year. It would seem that in 2013, you will continue to use Stage 1 criteria, but will have to comply with MU for the whole year, not just 3 months. This will apparently give the EHR companies like AC until Jan 1, 2014 to upgrade their software to collect Stage 2 MU data.