From the GeoJSON mailing list:
The GeoJSON Authors are proud to announce the finalization of the GeoJSON 1.0 Specification.
Representing more than a year’s worth of community discussion and development, the GeoJSON specification describes an easy to use, extensible format for transferring geographic data over the web. With support in more than 20 different applications, GeoJSON is already quickly becoming a de facto standard for transferring geographic data in a JSON format. The finalization of the spec represents the final step in formalizing the GeoJSON format for encoding this data.
More information on GeoJSON can be found at http://geojson.org/ , or from the GeoJSON mailing list at http://lists.geojson.org/listinfo.cgi/geojson-geojson.org .
OpenLayers has been a long-time supporter of GeoJSON, and was one of the first web-mapping clients to support read/write of GeoJSON.