Problm linking to Mozilla nightly builds

[Peter Torpey]

I tried linking to the Mozilla nightly builds of Firefox and Thunderbird 
by adding the following line:
deb http://ppa.launchpad.net/fta/ubuntu jaunty main universe
in the file /etc/apt/source.list

As root, I did the command
apt-get update
in order to update the list of available packes.
This complained that there wasn't a public key available for this link.

How do I fix this and properly link to the nightly builds so that I can 
take advantage of the improving accewssibility?

Also, as a side note, should I be updating Orca more regularly in a 
similar fashion?

Thanks.

--Pete