Hi Simone,
With Martin, we though that it would be safer to leave aside Joda Time for now because introducing new dependencies in metadata or referencing library (where a temporal framework should probably lives) is a sensitive issue. We would like to avoid adding an additional layer of controverse on top of JAXB in metadata. We see the issue as different than JAXB in that there is no alternative to JAXB in the JDK, while there is alternatives (admitly inferiors) to Joda in current JDK.
Furthermore Joda is expected to be included in JDK 7, but under another name (see Date And Time API JSR 310). We would like to wait for its inclusion in JDK 7 in order to use the Java classes with their appropriate name, and thus avoid breaking public API during the switch from Joda to JDK 7.
For un/marshalling threads we use JAXB and the implementation is based on jdk6. Currently I have implemented the most important classes of ISO19108 and I have just begun the JUnit tests.
Mehdi.