Yes. Done some fairly comprehensive eval of Riverbed and other WAN opt solutions.
In the right circumstances it can pull off some pretty amazing results, but beware the website hype; it's based on CIFS/MAPI traffic which is notoriously inefficient. Even so, with a bit of man-in-the-middle work you can even get great results with dynamic encrypted traffic but bear in mind it only really shines with TCP traffic.
It's VERY expensive! Beware the pricelist aswell, the 155Mbps appliance means 155Mbps optimised, not raw!
Depending on the requirement Citrix is frequently cheaper...
Nothing can work the magic that a properly specced WAN will.
Sorry lad, not true.