Earlier quoted context omitted.
Even though their Amazon S3 Transfer Acceleration Speed Comparison page [1] do test uploads only, this new feature is documented to accelerate downloads as well. I guess optimized WAN network routing between S3 regions and their edge locations usually beats regular internet routing. [1] http://s3-accelerate-speedtest.s3-accelerate.amazonaws.com/e...
I didn't mention that because it wasn't in the official blog post, but you're correct. My assumption is that AWS has their own dedicated fiber/private connectivity between edges and regions.
> With today’s announcement, the edge network also helps to accelerate data transfers in to and out of Amazon S3.