S3 support Virtual Hosting

This is good news - S3 supports the Host header in HTTP requests. I had been meaning to write about the security holes is storing different people's data within the same domain - as soon as two people host javascript, then 'cross site scripting' becomes possible within one host domain. This enhancement allows folks to trivially avoid that problem (assuming people want to host HTML and Javascript on S3 - not it's advertised purpose).