Rails : HTML only?

Hi,

Last week, someone asked me if Rails is limited to (r)html (so webapps)
only.
My first answer was 'yes' - because I think the inner workings of Rails
is http-specific.
After some googling, I came up with this link :
http://weblog.rubyonrails.org/2005/01/25/rich-clients-with-rails-and-xul/
and http://www.zedshaw.com/projects/cookbooxul/ , where Zed Shaw does
a little rails-hacking and uses XUL for the V in the MVC... and got a
bit excited.

So I was just wondering... Is Rails really limited to html?
I believe it would be nice to use Rails - or more the philosophies of
Rails - for a desktop-application oriented framework.
It would mean to lose a bit of simplicity, but gaining a lot more
flexibility.

Just wondering - Is this possible with Rails?

Don't get me wrong - I enjoy Rails for developing webapps, but I would
love it even more if I could use it all the time!

Well its HTTP specific, but that means that it is easily applied to anything
that you could normally send over HTTP, which does include web-services
a-like stuff, XML and dynamically formatted text files.

In fact there is a proliferation of View technologies in Rails. rhtml templates
are probably the most familiar technology, but by no means the only one.

That's correct. And I could do that - but that means also more work
when creating the GUI (as by using the http protocol all the time) with
the ruby gtk-bindings.
What I mean is a system like Rails: the variables of the controller are
visible in the view for example.

Thanks for the clarification,
that makes a lot of sense. It's not that I needed it for my current
project, but the person who guides my project did ask that question.