The latest published Internet-Draft is v5 (draft-wright-json-schema-00, draft-wright-json-schema-validation-00, and draft-wright-json-schema-hyperschema-00) published 2016-10-13. The specification is split into three parts:

JSON Schema Core	defines the basic foundation of JSON Schema
JSON Schema Validation	defines the validation keywords of JSON Schema
JSON Hyper-Schema	defines the hyper-media keywords of JSON Schema

They are also available on the IETF main site: core, validation and hyper-schema.

The meta-schemas are the schemas which define the JSON Schema and Hyper-Schema formats.

The latest meta-schema is draft-04. A future release with additional keywords will be published in the near future.

Core/Validation Meta-Schema	Used for schemas written for pure validation.
Hyper Meta-Schema	Used for schemas written for validation and hyper-linking.

These sample schemas describe simple data structures which can be expressed as JSON:

Geographic Coordinate	a location as longitude and latitude
Card	a microformat-style representation of a person, company, organization, or place
Calendar	a microformat-style representation of an event
Address	a microformat-style representation of a street address