These VRF features are supported in the IP Plus feature set on the 2851:
VRF Aware Cisco IOS Firewall
VRF Aware Dialer Watch
VRF aware IPsec
VRF-Aware VPDN Tunnels
"Virtual Routing and Forwarding (VRF) Aware Cisco IOS Firewall applies Cisco IOS Firewall functionality to VRF interfaces when the firewall is configured on a service provider or large enterprise edge router. Service providers can provide managed services to small and medium business markets. VRF-Aware Cisco IOS Firewall supports VRF-aware URL filtering and VRF-lite (also known as multi-VRF customer edge [CE])."