ok, I think we managed to switch http://www.kathack.com over to S3. Thanks for the tip!

from my understanding, S3 optimizes throughput but not latency. I'm not surprised that his performance serving from S3 is perfectly fine, but I think the "answer" is to skip straight to CloudFront. CloudFront can mirror directly from your appserver, or from S3, it doesn't matter.

update: did a little googling, and found only anecdotal evidence that latency to S3 is fine but not awesome:

http://www.cloudclimate.com/s3/

http://www.codeswimming.com/blog/2010/04/amazon-s3-and-cloud...

http://www.slideshare.net/ehwinter/using-amazon-cloud-front-...