I have a question to both groups (JAXB and JSONP).
You probably heard about EclipseLink MOXy project . It is (among other features) another JAXB implementation. It is also possible to map JAXB annotated Java classes to and from JSON stream.
In JDK by default, there are two distinct projects to manage XML and JSON, namely JAXB-RI  and JSONP-RI  but they don't have anything in common. More so, there is no standard for mapping Java objects to JSON output (and the other way) - JSONP is the low-level API to serialize & deserialize JSON "by hand". The only way to do the Java-JSON binding is to use libraries like MOXy and it's default one for GlassFish .
Questions to JAXB leaders: - Does this mean that MOXy is the default JAXB implementation used by GlassFish?
- Are there any plans to create a new JSR for Java-JSON binding e.g. Java API for JSON Binding?
- Are there any plans to include support for JSON marshalling & unmarshalling in JAXB (e.g. based on JAXB annotations)?
Questions to JSONP leaders:
- Are there any plans to include JSON validation (like XML schema validation)?
- If "yes" for the previous question - how do you want to define JSON schema - using JSON or XML Schema?