XZ for Java 0.4 is now available: http://tukaani.org/xz/java.html
There are some minor fixes to the old code. Support for random access decompression is a new feature. Threading is missing but it's easier to add it to this code than to liblzma in XZ Utils. This is probably the last release before 1.0. I don't have anything planned before 1.0 but maybe someone finds something that could be improved. :-) -- Lasse Collin | IRC: Larhzu @ IRCnet & Freenode