When trying to use rescue image (from 31-Aug-2006), Anaconda is asking for RHEL installation CD even rescue CD is inserted. I mounted DVD image, typed URL and rescue mode starts after some time. Rigt after that (probably after downloading something from FTP server), a popup window flashed: "Detected local media". Strange...
You're booting from a CD and doing an HTTP/FTP install? Are you seeing a message about failing to retrieve repodata/repomd.xml?
This should be fixed in the next beta.