I have reproduced the error under the version of nautilus-gksu in hardy-updates, 2.0.0-5ubuntu3, and have verified that the version in hardy-proposed, 2.0.0-5ubuntu3.8.04.1, fixes the issue. I verified that it works properly even in the case of a filename that begins with a space. I also verified that gksu and gksudo continued to function as expected.
I have reproduced the error under the version of nautilus-gksu in hardy-updates, 2.0.0-5ubuntu3, and have verified that the version in hardy-proposed, 2.0.0-5ubuntu3. 8.04.1, fixes the issue. I verified that it works properly even in the case of a filename that begins with a space. I also verified that gksu and gksudo continued to function as expected.