The JDBC 4.0 PFD contains many clarifications to the JDBC spec including the JDBC API docs. The majority of the changes are reflected in b91 of Java SE 6, Mustang. Some of the areas of change include:
Revamping the SQLXML interface, which which I blogged about earlier
Improvements to the JDBC compliance chapter which now incorporates the requirements for JDBC drivers in a Java EE environment...
