Please label /var/lib/mock and all subdirs as mock_t (or another unique label of your choice) so that mock can be made to work in SELinux-enabled systems without manual intervention. This change should also be done to -strict as well if feasible. A backport to FC3 might also be useful.
Further proof that one should not file bugs when half-asleep. Also required is a domain that has full read, write, and execute access in /var/lib/mock.
This should be running under unconfined_t and should be able to work. You need to get someone to write the policy for this package. We only write policy for packages that we ship. If you or someone else writes the policy, I can get it upstreamed. Dan