Quoting Benji York from gmane.comp.web.zope.devel:
The rendering framework is pluggable and it's pretty easy to add new rendering options for other testing systems (twill, etc.).
The testrecorder is currently in "beta" form, but is very handy, so if anyone wants to use/market/improve/add tests for it, go ahead. :) Get it via Subversion at svn://svn.zope.org/repos/main/zope.testrecorder/trunk
It is very cool.