Amazon added a DNS service to their stack of web services today The service is called Amazon Route 53.
Now you can host your domains DNS with Amazon for $1.00 / month per zone and .50 cents per million queries.
You can use the Route 53 DNS
for your Amazon infrastructure as well manage external resources as well.
For my personal domains I tend to use the DNS that comes with the domain at GoDaddy. I have setup DNS services using Amazon EC2 instances, and now can stop doing this and rely on their new Route 53 DNS