I haven't release a new version of XSieve, and there are no user-visible changes, but it doesn't mean I do nothing. I've been working on low-level technical issues and writing documentation.
If you are interested, here is a link to ChangeLog:
I've started a grand testing. I've written a sketch of a naive converter from XSLT to XSieve, and converted DocBook XSL stylesheets to XSieve. Now, running DocBook XSieve and comparing the result with the expected data, I find bugs. Some of them are very hard (right now I'm trying to identify an issue which is probably related to the garbage collector). I hope to fix everything during the next week.