The Xineo project maintains various open-source Java packages, mainly targeted to XML management. Available packages include :
Downloads are available at SourceForge's download center.
All XML-related sofware is now available in a single global package (current version is 1.1.0).
There is a mailing-list targeted to Xineo users for question asking and release announcements. You can also contact me for any information about Xineo. You may also grab more information about Xineo projects on its SourceForge page.