We ran in a small HR security issue, where it seems that future hires are not visible for a manager, when using a security profile that lists all employees in and under the manager's organization.
When digging into the Oracle code, we understood why.
Please enjoy the comments and the trunc( sysdate) piece of magic, found in the hr_security_internal package.
FUNCTION get_effective_date RETURN DATE
-- Default the effective date to sysdate. This could potentially
-- be used in the future to set the effective date to the
-- date-track effective date, but as it stands now, security
-- is also determined as of sysdate.