What are your values of

M-x getenv SSH_AGENT_PID
M-x getenv SSH_AUTH_SOCK

?
I assume that your problem is that these variables are only set in terminals
but not in programs started from GNOME/KDE/... (where .bashrc and the like
are not sourced).
Hence, tramp will not know anything about the ssh-agent and prompt you for
the password. In that case you should try to find a way to make your
ssh-agent known to the session.
For example, I am using KDE, and there is a script in /etc/kde/env/ with the
following content:

$ cat /etc/kde/env/agent-startup.sh
# Agents startup file
#
# This file is sourced at kde startup, so that
# the environment variables set here are available
# throughout the session.

# Uncomment the following lines to start gpg-agent
# and/or ssh-agent at kde startup.
# If you do so, do not forget to uncomment the respective
# lines in KDEDIR/shutdown/agent-shutdown.sh to
# properly kill the agents when the session ends.

if [ -x /usr/bin/gpg-agent ] && [ -z "${GPG_AGENT_INFO}" ]; then
  eval "$(/usr/bin/gpg-agent --daemon --pinentry-program
/usr/bin/pinentry-qt4)"
fi
#
if [ -x /usr/bin/ssh-agent ] && [ -z "${SSH_AGENT_PID}" ]; then
  eval "$(/usr/bin/ssh-agent -s)"
fi

and a similar script to shut the agents down.

Cheers
Bastian


On Thu, Jul 22, 2010 at 4:00 PM, Gary <help-gnu-emacs@garydjones.name>wrote:

> I have ssh from the console setup to use authentication using
> keys. Works fine.
>
> Tramp on the other hand...
>
> Well, after the event I do see the requests to "Enter passphrase for
> key" but I am not actually prompted for them when I try to open a file
> on the remote host. Instead I am just asked for a login password. Any
> idea what is going on and how to fix it?
>
>
>


-- 
Bastian Beischer

I. Physikalisches Institut B (RWTH Aachen)
Sommerfeldstr. 14
52074 Aachen
GERMANY

Office: 28-C-203
Phone: +49 241 - 8027205