the last version of red hat is Fedora core 5 and you can download it in **broken link removed** there are 5 images, OS and software, there is also documentation about fedora.
Redhat is not releasing any more free versions. But they are started a new open distribution named Fedora. Fedora disk images can be downloaded from **broken link removed** and its free.
Redhat is still distributing commercial enterprice editions, which is not free.