Seems like it's ok so far. So I released it rather than continuing to sit on it. I've done a lot of work on the manual to cover the areas that were covered poorly or not covered at all. There's still a lot of material to cover, but we're definitely making measurable progress in that direction.
Steven Armstrong did a lot of work to get mod_python, WSGI, and Twisted supported. I'm not sure why anyone would use WSGI or Twisted, though, since they don't appear to make much difference in how fast PyBlosxom works. mod_python definitely helps, though. Steven has some runtime statistics at http://thread.gmane.org/gmane.comp.web.pyblosxom.devel/1397.
This feels like a good release. We met some goals, we didn't sit on it forever, the documentation is an order of magnitude better than it was for the previous version (though it has a long way to go, still), and we fixed a bunch of bugs.
Having said that, it's definitely not necessary for people to upgrade. I think if your blog works and you don't need to futz with it to get additional functionality, leave well enough alone.