Looks like Sun folks silently updated Java 6 to use JAXB 2.1 API. The fact that Java 6 was shipped with old version of JAXB used to be a lot of pain. Hopefully we don't need to mess with endorsed directory workaround anymore.
I run a diff and it turns out that JAXB API shipped with JDK 1.6 is almost identical to 2.1. It has only one significant difference from 2.1.6: Class javax.xml.bind.ContextFinder refers to a different location of Context Factory. In com.sun.xml.internal.bind.* became com.sun.xml.bind.*
Bottom line: if you want to use JAXB 2.1 with 1.6, simply add JAXB implementation in your classpath. No need to use Java endorsed mechanism anymore.
P.S. Also the following frequent error is now a history: "java.lang.LinkageError: JAXB 2.0 API is being loaded from the bootstrap classloader, but this RI requires 2.1". If you still see it with JAXB 2.1 in classpath simply update your Java 6 to the latest version (I tested it with 1.6.0_04-b12+ which was released in Spring 2008).
