Does anyone know, if there some plans to evolve Javadoc, in a somehow-standardized way?
The corresponding JSR (JSR 260), which specifies enhancements to Javadoc, has been voted out of JDK 7 (for now). An overview of what was planned (from this site):
Upgrade Javadoc to provide a richer set of tags to allow more structured presentation of Javadoc documentation. This JSR covers: categorization of methods and fields, semantical index of classes and packages, distinction of static, factory, deprecated methods from ordinary methods, distinction of property accessors, combining and splitting information into views, embedding of examples and common use-cases, and more.
The overall outlook for JDK 7 is pretty grim.