I just installed scons from Fedora, and got a message from yum indicating it was not signed:
Package scons-0.97-2.fc7.noarch.rpm is not signed
But:
[root@charlesc ccurley]# rpm -K scons-0.97-2.fc7.noarch.rpm scons-0.97-2.fc7.noarch.rpm: (sha1) dsa sha1 md5 gpg OK
(On a copy I pulled in separately from the "yum install" command, so it may be a repo updating issue).
When I then installed from the local copy, yum accepted it and installed it. But yum won't accept a repo copy.
This makes me wonder if at least one repo has a corrupted copy.