I'd like to show some extra information to people who are browsing a contribute
capable site. E.g., having a hidden div with special edit instructions at the
top of the page that only shows if the browser type is Contribute (and probably
from a specific domain / ip range).

However, all my HTTP header splunking shows that Contribute doesn't seem to
supply any special identifying info. In fact the user-agent header is the same
as IE.

So, does anyone know a way to identify Contribute at the server side?

Also, it would be nice if there was a way to have a locally defined Contribute
schema that would launch contribute from the web browser (I know about the tool
bar...). That way, authorized users (in the web app sense) could see a link
like:

<a href="contribute://site/currentURL" >Edit this page in Contribute</a>

You could then be browsing a site with IE/Firefox/Opera and click to edit,
even if you have turned of the Contribute tool bar.