The FAA this week released its final rule on ADS-B equipage in the mid-term, mandating ADS-B Out capability by 2020 for every aircraft using airspace where a transponder is currently required. Predictably, GA groups feel that they will be made to shoulder a large financial burden that ultimately will benefit airlines and air travelers rather than private pilots, although some concessions to general aviation were made in the final rule.
Some good resources to understand the consequences and subtleties of this rulemaking: