Have you guys considered selling a Hamachi VPN client for the iPhone? Cisco's got an anyconnect vpn app that actually sets up a vpn connection that the entire phone can use when you're not in the app. I would buy it in a heartbeat.
After realizing the importance of online security, iPhone users must look for VPN providers who have been in the business for some time and got state of the art technical infrastructure. Here, you have to use discretion in selecting the best iPhone VPN provider based feedback of past customers, affordability, quality of service, etc.
I have an ISP that uses NAT that I can't control. Traditional vpn clients haven't been successful for me, but hamachi works great. I have a linux server that I'd love to have access to from my ipad/iphone. Thanks.