This bug is bit a tricky case.

Harshad: You might try the "work-around" suggested by Antoine. But that
is just a work-around. not a fix. Add an entry to gconf-editor like any
other. ( google).

The actual bug seems to be with gnome-open which is unable to handle ftp
urls.

$ gnome-open http://www.google.com
02:44 PM:senthil@:~/python/trunk/Lib
$ gnome-open ftp://ftp.freebsd.org
Error showing url: The specified location is not mounted

Google for (gnome-open + bug + ftp) you will be given the list of bugs.

In my case, I think the user-installed firefox has taken the control of
the ftp mimetype and in your case, gnome-open is the default and it is
failing with ftp.

As per suggestion just work-around it with ftp handlers and it should
do. May check with ubuntuforums for suggestions too.

There is a no problem with the webbrowser.py and I am closing this bug
as Invalid.