Wow.  Pure Java edition of Berkeley DB is out.  I guess pure Java version of Berkeley DB XML is coming as well.  As to the performance, I haven't checked it myself but if this quote means anything, I think this is a major event for Java developers:

"With Berkeley DB Java Edition, we have a simpler setup, a 3x increase in data import speed, a 5x increase in performance and a 10x decrease in disk storage requirements."

–  Eric Jain, Swiss Institute of Bioinformatics