So, a 300Gbps DoS attack. Biggest ever. So big, it caused problems at the large interexchange points in tier one carriers.
For more information on the attack, CloudFlare has some excellent information.
http://blog.cloudflare.com/the-ddos-that-almost-broke-the-internet
The HackerNews discussion also indicates that some ADSL modems forward DNS requests to the internal network through NAT, so you should check if your IP address is in the list of open resolvers if you're running a DNS server:
http://dns.measurement-factory.com/surveys/openresolvers.html
There are many NZ organisations on the list of open resolvers. Perhaps we should think about naming and shaming them?
http://dns.measurement-factory.com/surveys/openresolvers/ASN-reports/latest.html