The [https://fedoraproject.org/en/verify Verify] link on the [https://fedoraproject.org/get-prerelease pre-release download page] has information for the previous release.
Right now to verify a Fedora 15 alpha download, I have to go searching for the right CHECKSUM file on the ftp sites.
It should be easier to verify the pre-release downloads.
This has been fixed. The verify page now includes the latest Beta links to the checksum files.