According to a cryptic announcement posted to the Fedora-Announce mailing list, the open-source group is investigating an unspecified "issue in the infrastructure systems" that has resulted in widespread service outages.
In the note, Fedora maintainers recommend that end users avoid downloading packages on Fedora systems, which strongly hints at a security-related problem:
A follow-up message posted over the weekend said the investigations were continuing but there are no details available on the cause of the problem.
Efforts to contact Red Hat Fedora maintainers have so far been unsuccessful. I will update this post as necessary.
* Image credit: jgbrl's Flickr photostream (Creative Commons 2.0)