I was having incredible difficulty flashing my device under Ubuntu Flight 6/7 (a beta version from a few months ago), and now that I updated to the official Ubuntu 6.06 it worked like a charm.

Just a heads up to anyone experiencing the "USB Device Not Found" BS from flasher or flasher-2.0 with an older/beta version of Ubuntu. Oh one more thing, you have to have root access to access USB, so use "sudo" or the root terminal. Hope this helps someone!