Actually, if you look in the Device Manager, you do see a TPM device, and as Bitlocker is used to encrypt the drive contents, this ties in with it having one.
I saw a BitLocker option but assumed it was a remnant of the Windows 8 OS and not a "useable" function of RT.
I had heard from my MS source that there was no TPM, but it's possible they were mistaken.
Either way, VPN is possible with either MS's cooperation or the OEM vendor's development.