One of the interesting enhancements, that are happening recently to Xerces code base, is XML Schema 1.1 implementation.
The Xerces-J team motivated me to implement some of the XML Schema 1.1 features into Xerces. I've started with the implementation of XML Schema 1.1 facility, "assertions".
I've completed quite a bit of work regarding this, and am hoping that the assertions support I'm writing would be available in Xerces-J in near future.
2008-11-04: Xerces team approved my work so far for assertions implementation, and have committed my patch to the Xerces code base. In the coming weeks, I would be working on integrating XPath 2.0 processing for assertions.