A parking lot timeout and callback to the extension that parked the call is available already in UCx 3.0. In the release 4.0, there are additional configurable options for the parking lot - for example you can select a destination where you want to send parked calls after a timeout.
The "Held Line Reminder" feature is available on release 4.0 - the feature functionality is the same as on Norstar/BCM.
A few more Norstar/BCM features added to 4.0 that might be worth mentioning - F77, F806, F811