Just to clarify--you're seeing something like
then a bunch of checksums for various isos.
It's confusing--those checksums are actually sha256 sums.
As trainstroker points out, that big SHA1 refers to the GPG sig. It does NOT refer to the checksums.
I think they were planning to get that fixed by the F13 release. Folks, who I assume work with them more than I do tell me it's really easy to tell by the length of the checksum, but to me, it's just a long string, whether it's 50 something or 70 something characters.
It is mentioned in the documentation (if you go to the download page, you'll see a link about verifying), but don't worry--even the nice folks at distrowatch were confused by the layout.