Reports here:
http://www.nytimes.com/2013/03/27/technology/internet/online-dispute-becomes... http://www.bbc.co.uk/news/technology-21954636
And some technical details from Cloudflare:
http://blog.cloudflare.com/the-ddos-that-knocked-spamhaus-offline-and-ho http://blog.cloudflare.com/the-ddos-that-almost-broke-the-internet
And here a tool to check whether you are running an open DNS resolver.. If you're an ISP, you might want your customers to run it..
http://www.thinkbroadband.com/tools/dnscheck.html
Cheers,
Mat