I wanted to install the newest version of the terminal client terminator in ubuntu hardy.
You can find terminator here:
http://www.tenshu.net/terminator/However after I added the apt-source and ran "apt-get update" I got stuck a the following error:
"W: GPG error:
http://ppa.launchpad.net hardy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 978228591BD3A65C"
After some searching I found this solution:
gpg --keyserver
wwwkeys.eu.pgp.net --recv-keys 978228591BD3A65C
gpg --armor --export 1BD3A65C | apt-key add -
then run apt-get update && apt-get install terminator