I changed my page to sitemap.xml but it doesn't
publish it!
Sitemap produces a number of files. There is the
default 'user viewable' page which is a html file
(for instance
here). It can also
(optinally) produce a 'sitemap.xml' file.
This file is uploaded with any graphics,
etc. that you have to the 'files' directory
under the sitemap page (note that the
'files' directory is not always called
'files' but will always have the word
'files' in it's name)
One improtant tip that sometimes catches people.
What you don't want to do is change the name of
your sitemap page to sitemap.xml

Instead to get the sitemap.xml file created just
select the "Create 'sitemap.xml' file for Google
to Index'
I hid a page in the menu and now I can't unselect
the 'hide in sitemap' button
If a page is marked 'hide in sitemap' and you
can't unselect it then you probably have 'Hide
Pages...' in the options tab. Unselect it if you
want to hid pages in menu but allow them in
sitemap.xml