It was the flash-player plug-in. I forgot to write down the exact package name when it happened, but once the upgrade is finished I will find it and update the post. It was a GUI screen asking for acceptance to the licence agreement, so I suppose that was Debconf.
** Tags added: edgy flash -- Update waits indefinitely for user input https://launchpad.net/bugs/67338 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
