The HL7 FHIR (pronounced “fire”) standard has been under development for a while. It became a Draft Standard for Trial Use (see DSTU Considerations) in Jan 2014. The recent announcement of the vendor collaboration Argonaut Project has fueled some "interoperability excitement"™.
The best technical overview I've read is this whitepaper: The HL7 Games Catching FHIR. In particular, it does a good job of comparing FHIR with HL7 v3. Summay:
HL7’s FHIR™ standard has learned from the mistakes of HL7 v3, and is surprisingly delightful.
