RFC 2764 and VPRN

Is anyone aware of current implementations of Virtual Private Routed
Networks in use by carriers as described in the VPN RFC 2764?  Or if anyone
can point me in the direction to find more information on VPRN
implementation advantages and disadvantages besides that described in the
RFC.

Thanks,

Jason Rakers
Network Engineer
Allegheny Energy
jrakers(_at_)alleghenyenergy(_dot_)com