"What does Googlebot see when it accesses my page?"
googlelabs.com
googlelabs.com
The other reason why this is useful is that in larger complex deployments, there may be requests that get throttled, dropped on the floor, etc. as an automatic means of shedding load. We have such a mechanism at StyleFeeder, because we have so much robot traffic. Other times, load balancers and the like will inject stuff into the HTTP request stream in a way that isn't obvious when you're working in a dev environment.
Are they advocating specializing pages for the Google bot?