OpenVPN is an awesome implementation of a virtual private network, far superior to the traditional ipsec implementations.
Unfortunately, different vendors of networking equipment support ipsec to various degrees, making interoperability of devices an issue. OpenVPN runs on software and can be run on Linux, Mac, and Windows operating systems. OpenVPN Gui makes it a home run for Windows business users, who will find it just as good as Juniper Networks or Cisco competitors who charge a lot of money for equipment and licensing! Tunnelblick makes the Mac experience a breeze. Some DNS tweaks are required sometimes, however, whereas the Windows client is super-simple. After I installed OpenVPN, I through my old Netscreen/Juniper POS out the window. It’s never failed me. Its definitely an open source project to support.