"trading some consistency for availability can lead to dramatic improvements in scalability"!???
Wow! That's just great! Why not go all the way: an 100% available system with no consistency whatsoever? Oh, wait, we already have that in Google App Engine!
Neither of these is reasonable. You can't yield consistency - it is more important than availability. What's the user in having information available at 100% when you don't know whether it will be consistent?