The IS has been served by the ISC SNS@ISC system for some time now and together these two systems mean that the response time for delegation record lookup for .IS domains will be much improved globally. ISNIC will also have better defenses against various types of resource depletion on the .is nameserver set.
See also RFC3258 - Distributing Authoritative Name Servers via Shared Unicast Addresses and RFC1546 - Host Anycasting Service