I also have the same issue.
I have Mint8 installed. I install the usb creator, and it worked.
It installed version 0.2.8
But on both system the version numbers differ from what aptitude shows. On Ubuntu it has a higher version in aptitude. This is the one that fails. But still interesting of the different version info.
From current Ubuntu:
Thanks for creating the bug report. I will "me too" it.
$ usb-creator-gtk --version
$ aptitude show usb-creator-gtk
Automatically installed: no
Maintainer: Ubuntu Installer Team <email@example.com>
Uncompressed Size: 197k
Depends: python, python-central (>= 0.6.11), usb-creator-common (= 0.2.16),
python-gtk2 (>= 2.12), python-dbus, python-gnome2
Description: Ubuntu startup disk creator for GTK+
This is a simple utility designed to make startup disks from Ubuntu CDs.
This package contains the GTK+ client frontend.