Bluestream just released the next version of their XStreamDB XML database server.
Perhaps the biggest part of the release isn't even in the software - it's in the licensing. It's now about half the cost of what we paid, and it's free for teaching. If you're teaching XML, you can download it and just go. Student projects, etc... It's all good.
There are also a bunch of great changes under the hood - scored search results, performance improvements, and other goodness.