Monal is unique on iOS because it is able to fully multi task without using  any private APIs. However, I stumbled upon this after setting up the iOS openVPN client and was amazed at how it worked.  It actually hooks into the native VPN interface using Apple authorized private APIs.  If you are an iOS developer, this is an absolutely fascinating read. I didn’t know this was even possible!

http://blog.michael.kuron-germany.de/2010/09/ios-4-1-undocumented-vpn-api-used-by-cisco-anyconnect/