As fast as a duck
That's me on my travels, according to my personal annual report from Dopplr. It's a lovely thing that has already gone up on my wall, and I'm pretty sure that it's the first time that a social/online/media network thingy has actually given me something tangible. Which suggests one way that differentiation will start to occur - is it possible to take your facebooking and twittering into the real world and make it tangible? Will you want to?
The other, is of course, language: taking something abstract like miles traveled, and turning it into comparable, graspable facts. Like miles to Saturn. Or waddle speed.