sudo ./launchpad-update

An user from the UbuntuForums (blackgr) has made a script that checks your current distribution version (so it works from Hardy to Jaunty and probably Karmic) and then it checks your system for all Launchpad sources and will download and install the OpenPGP keys for you.You can download it from here To use it, simply extract the content of the archive, then use the terminal to navigate to it's directory and type this in the terminal:Then just wait for the OpenPGP Launchpad PPA keys to be imported.