According to https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=130887:
This is the master Fedora Core 3 "BLOCKER" bug. Any bug in Red Hat bugzilla which would be considered a "stop ship" bug a.k.a. a "ultra brown paper bag" bug, can be marked for consideration to be a release BLOCKER by adding this bug to it's "Blocks:" field.
Anyone in the community who wishes to nominate bugs for FC3Blocker status, should discuss them on the fedora-devel-list@redhat.com, and once concensus has been reached, someone can flag them as FC3Blocker, or alternatively as FC3Target.
This bug has the bug alias "FC3Blocker" for easy access and blocker flagging.
I think https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=132947 is a definite candidate:
Running 32 bits applications on x86_64 FC distributions with kernels based on 2.6.8 (2.6.8-1.521 and 2.6.8-1.541 currently) generate continuous memory leaks. Returning to the previous 2.6.7 based kernels turns this behaviour off.
The bug comes from FC2 (so testers need not run FC3t2 to verify).