Anyone operating in the health tech universe for the last few years knows that open health data has been and continues to be a major theme. Current White House Chief Technology Officer Todd Park started talking (NO, YELLING!) about “data liberacion” back in 2010 when he was tapped to be CTO for the Department of Health and Human Services (HHS). Since then, Park and his HHS successor, Bryan Sivak, have moved heaven and earth to liberate huge amounts of valuable health data.

Health 2.0 startups have swarmed all over the data, using it to build ever more useful applications and tools. Data that was once siloed and accessible to only a few is now available to millions through online services like iTriage, Vitals.com, and Castlight Health. With each passing day, innovators figure out new ways to use and combine data sets in ways that no one in the federal government could have ever imagined.

In the last few weeks, however, the feds have upped the “data liberacion” ante, releasing a number of new datasets that could have a totally disruptive impact on the established health marketplace. On May 8th, the Centers for Medicare and Medicaid Services (CMS), released a dataset showing inpatient hospital charges to Medicare for 100 of the most common inpatient diagnosis codes. CMS followed up on its initial salvo on June 3rd, also releasing outpatient charge data for 30 of the most common ambulatory payment codes.

Why is this important? Prices charged to Medicare were formerly top-secret and closely guarded. Hospitals and health systems kept this information confidential because making it public could impact how they compete with other provider institutions and could also impact complex price negotiations with private third party insurers. The world has suddenly changed. Default price transparency is the new norm for providers working within the Medicare program (at least for the most common diagnoses), and we expect more transparency to come down the line from the feds and the states.

To say that there has been a lot of interest in this data is an understatement. The datasets have been downloaded more than 300,000 times already, and the number of downloads continues to increase. Geolocation data shows that the data has been downloaded by users in every state in the U.S. and also by users in more than 130 different countries. A prize competition using the data, which Health 2.0 is running with the Robert Wood Johnson Foundation (“RWJF Hospital Price Transparency Challenge”), is already one of our most popular challenges to date, despite being launched only three weeks ago.

Expect to hear a lot more about this CMS data over the next few weeks and months. The “liberacion” of these sensitive sources of information is an important new chapter in the transformation of our health care system.