I was just going to say that I thought that there were implications for mapping the "www" subdomain like this, because S3 didn't support root domains, but that's been changed in the last few months:
edit: There are consequences relating to mx records, such as if you want mail service on the domain. From a comment:
> Just be careful here with doing CNAMEs on root domains. Things like email will break because the MX records are no longer visible behind the CNAME. Gmail for example won't send emails to domains with a CNAME as root.
I don't believe using Amazon's DNS like this will result in a "CNAME on the root domain" (a technically invalid situation in all cases, since a CNAME can't co-exist with other records...), I think it causes Amazon to return an A record which has been computed by being internally aliased within Amazon's DNS system.
Edit: Amazon has actually clarified this point in the comments of the article as well -
‘You're completely right about CNAMEs at the domain apex, they do tend to break MX and NS records. When this feature is used with Route 53 ALIAS records, no CNAME will be present - behind the scenes the ALIAS record links directly to the S3 "A" record data.’
http://aws.typepad.com/aws/2012/12/root-domain-website-hosti...
(and plus, there's redirection)
edit: There are consequences relating to mx records, such as if you want mail service on the domain. From a comment:
> Just be careful here with doing CNAMEs on root domains. Things like email will break because the MX records are no longer visible behind the CNAME. Gmail for example won't send emails to domains with a CNAME as root.
Related article: NPR's apps team had a nice post about how most of their projects are S3 hosted flat files: http://blog.apps.npr.org/2013/02/14/app-template-redux.html