While waiting for official announcement I see that FreeBSD 8.0 iso file just replace 8.0RC3.
Quick download iso file for FreeBSD 8.0 Release :
Update via source using csup or cvsup
set to :
RELENG_8_0 for release
or
RELENG_8 for stable
Update via freebsd-update :
freebsd-update upgrade -r 8.0-RELEASE