ADCs are also quite capable of accelerating applications, which essentially duplicates much of the functionality offered by WAN optimization products.

Application delivery involves all aspects of delivery: routing, security, availability, acceleration, and optimization. Whether that range of functionality is provided in a single device (an ADC) or multiple devices (ADN) depends on the vendor and the network architecture/requirements.

WAN optimization is slowly being subsumed by more application specific technologies, and in general is being replaced wtih the concept of application delivery as a holistic focus. Consolidating from the bottom up (a la Riverbed moving toward an ADC model) or the top down (a la ADC vendor acquiring WAN opt technology) is really irrelevant in the big scheme of things, as it all ends up with the same focus: application delivery.

Lori