Devices using iOS 6.1 and later with VPN On Demand configured to "Always" will behave as if they were configured with the "Establish if needed" option. The device will establish a VPN On Demand connection only if it is unable to resolve the DNS name of the host it is trying to reach. This change will be distributed in an update later this month.
This will only affect iOS devices that are configured with an enterprise configuration profile that mandates traffic to certain servers always be through a VPN.
Essentially it seems VirnetX got a patent for a white list.