According to Brock Wolfe:
Has there been a change in Policy or configuration to prevent using MUUG web/ftp site for Fedora updates? I started to get error messages a week ago when trying to use redhat-update (reconfig'd to point to MUUG site as per newletter).
Gilbert told me there were problems with a couple of the mirror disks, causing the whole system to hang after the upgrade to FC3 on the server. They've been taken offline until he can get to the bottom of the problem or replace them. For now, you should probably use the U. of Calgary mirror.
http://mirror.cpsc.ucalgary.ca/mirror/fedora/linux/core/