Mark Hammond's work on PyXPCOM and a language-neutral DOM is well under way as of October 2005, and we believe that the glue code and bindings will be slim enough to be part of a default XULRunner or Firefox distribution when the 1.9 cycle is complete.
(N.B.: Mozilla does not intend to distribute the C-Python runtime with its applications or frameworks, and so application developers who wish to take advantage of these capabilities will need to provide for this dependency in their installers or packaging. Stub or streaming installer capabilities in the Firefox/XULRunner based on Gecko 1.9 will probably help a great deal to ease the extra download for Python-less users.)
== XUL' and XBL2 ==