iPhone 4 vpn

Not sure if this is the right forum so mods feel free to move it.

We've recently started using iPhones in the office after years of Blackberry users (I know). I don't have an iPhone but as I was playing around today I noticed a VPN option. What would this allow me to do? I imagine it could allow me to connect to our cisco devices but what else? Hopefully you guys are more knowledgeable than me on the subject.

 

VPN is a secure tunnel across the internet. The other end of the connection must also be configured.

It would allow a secure connection to a location, such as connecting to your office remotely and securely. When I connect via VPN to my office from home, I can see all of the devices on the network at the office as if I were another workstation on the premises.