I think there's a lot being said about blockchains because of Bitcoin, but other then Bitcoin I haven't seen any appreciable or desirable uses of them. At the end of the day, you're spending a lot of power and CPU cycles on something very transient.
EDIT: This is distinct from various toy applications of the "you could do this with a blockchain..."
EDIT: This is distinct from various toy applications of the "you could do this with a blockchain..."