On dingo kidneys
According to Ugo Cei on the cocoon-users mailing list, XML isn't worth "a pile of fetid dingo kidney" (TM) as a scripting language.
After writing lots of XSLT lately, I must agree.
I like XSLT as a transformation language. XPath in particular brings a lot of power to template matches and document tree queries. But the XML-based syntax is a pain, even more when you have to write some string manipulation or similar glue code.
Current dream this side of my screen would be to write Python code inside XSLT templates. I'm sure dingoes have dreams too...