Chapter 1 What’s New for FortiOS 5.0 : WAN optimization and Web Caching : Policy-based WAN optimization configuration changes summary : On the client side
  
On the client side
New features:
WAN optimization rules are removed and WAN optimization profiles are added. Profiles are configured in the client side.
New options in firewall policies: wanopt, wanopt-detection, wanopt-profile and wanopt-peer. wanopt-peer is used only on the client side for manual mode (wanopt-detection is off).
You can add Security features inspection to security policies that accept WAN optimization traffic.