Two releases are available:

Mono 1.0

For Fedora Core 1, please use: 
http://www.go-mono.com/archive/yum-repository/1.0/fedora-1-i386
For Fedora Core 2, please use: 
http://www.go-mono.com/archive/yum-repository/1.0/fedora-2-i386

Mono 1.1

For Fedora Core 1, please use: 
http://www.go-mono.com/archive/yum-repository/1.1/fedora-1-i386
For Fedora Core 2, please use: 
http://www.go-mono.com/archive/yum-repository/1.1/fedora-2-i386