@Linus, Mark: please say whether this works for you.
I think the extras archive is using the wrong key for maverick. It should be using the one that's in the ubuntu-extras-keyring (Ubuntu Extras Archive Automatic Signing Key) instead of this one (Launchpad Application Review Board PPA).
The link I quoted above is for lucid. You need a different key for maverick:
gpg --keyserver keyserver. ubuntu. com --recv 02FDF932
gpg --export --armor 02FDF932 | sudo apt-key add -
@Linus, Mark: please say whether this works for you.
I think the extras archive is using the wrong key for maverick. It should be using the one that's in the ubuntu- extras- keyring (Ubuntu Extras Archive Automatic Signing Key) instead of this one (Launchpad Application Review Board PPA).