This is the subject of this doc/essay:
http://json-template.googlecode.com/svn/trunk/doc/On-Design-Minimalism.html
You can reuse the "outside", aka a common "style" for your pages. Or
you can reuse the "inside", like a widget.
However in the Python version, I subsequently refined these ideas and
built it in more.
To reuse a widget you can use the "template" formatter, and
MakeTemplateGroup. e.g.
{bob|template user-profile}
{john|template user-profile}
"user-profile" being another template. (Now that I realize it,
MakeTemplateGroup should really be make_template_group to follow PEP8
naming...)
For the styles case, you can use expand_with_style. This is a little
more convenient than doing it yourself. You only have one template
dictionary.
The best examples right now are in the unit tests, e.g.
http://code.google.com/p/json-template/source/browse/python/jsontemplate/jsontemplate_unittest.py
It's possible to wire these same patterns into the JS version, or just
do it "manually" as I suggested in the doc.
These are in the latest version that I posted about a week ago to the
downloads section.
Andy