I think of this as an obvious (not necessarily beneficial for all, of course) step for a company which lives out of advertisement - i.e. what if they could capture your habits for browsing at the FQDN-to-IP time - wouldn't that add more to their knowledge base?
I think there are amazing opportunities to data mine and prevent fraud if you can get a percentage of your users using this. I'm really excited about the structured attacks that will be run against this thing (cache poisoning... and nastier)... if (for example) when their (or someone's) toolbar is installed, they ask if you'd like to use their "improved" dns service [perhaps they have the whole universe cached to reduce lookup times]. You'd sign up. And as the wave of software updates proceeds... well, talk about all your eggs in one basket. Smart ISPs will have an ACL ready to hijack external DNS requests for their whole network in the (inevitable) event something *bad* happens one day and you need to restore service to your customers faster than they can figure out how to fix it themselves. Just a thought. Deepak