The Apache2 xslt_filter is up and running on bart111, an openvz instance we use for exeprimental software. It has some nice parts - like the ability to return 304 status for non-modified documents, and it also works with apache2-mpm-worker so far.
There were a couple of gotchas in setting it up:
It wants apxs, but on my machine there was only apxs2. I created a symlink:
sudo ln -s /usr/bin/apxs /usr/bin/apxs2
There is an undocumented configuration setting for a default stylesheet, simply "XSLT_Filter default /path/my_xsl.xsl". I had to use this in my tests because I couldn't figure out how to get the xsl reference in the xml file to work.
Seems like this is a simpler version than mod_xslt, which still has the offensive signature in the resulting transform. I noticed that it is available in Mandriva, so hopefully it will go into debian at some point.