Looks like a typo in the service file: s|/usr/bin/tgt-admin|/usr/sbin/tgt-admin|
scsi-target-utils-1.0.24-3.fc17 has been submitted as an update for Fedora 17. https://admin.fedoraproject.org/updates/scsi-target-utils-1.0.24-3.fc17
Package scsi-target-utils-1.0.24-3.fc17: * should fix your issue, * was pushed to the Fedora 17 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing scsi-target-utils-1.0.24-3.fc17' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2012-11597/scsi-target-utils-1.0.24-3.fc17 then log in and leave karma (feedback).
scsi-target-utils-1.0.24-3.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.