Actually it was stated by a Microsoft expert in this thread that MS has NOT released the APIs for VPN client connectivity specifically.
If Microsoft wanted to make this happen, it would happen, period.
Enterprises are not buying up Surface Pro, why would they, the Surface Pro is a laptop replacement, not a solution for tablet placement. And as a laptop it is far too limiting to fill corporate needs. My enterprise is placing HP Elite Ultralights that
have a much larger screen, get 7+ hours of battery, ports galor, dockable, etc. Enterprises also need access to harddrives, memory, nics, even video cards, none of which a Surface Pro can allow.
Now take a Surface RT and place that as either a thin client or a tablet. It is far more productive a device then an iPad, IE10 renders corporate sites very well, mouse use for VNC/RDP is flawless, Office (needs Outlook but I hear its coming) etc. BUT....
almost no real VPN support other then what is baked into the desktop part of the OS. Its a deal breaker, makes it useless, pointless, a waste of corporate money when both iPad and Android have VPN apps from most major vendors.
As a complete side note, they also need to plug in Active Directory support. There is zero technical reason that this is not in there already other then they compiled Home instead of Pro version of W8.