I'm a little surprised that I had to pick this info out of an Amazon email newsletter as this seems to be pretty major news to me. What is Adobe's PR department doing to not send me some up-front info on this?

Anyways, Amazon Web Services is now offering a CloudFront based streaming service (supporting audio and video) that is powered by Flash Media Server. What this means is that everyone can now have an on-demand, highly available and highly scalable audio and video streaming CDN at their finger tips. How does this differ from traditional CDNs? The main difference is that you are only charged for actual usage, there are no tie-ins or long term contracts as is the case with most (if not all) of Amazon's Web Service offerings. Depending on Edge Server location the fees start at around $0.17 per GB of transfer up to the first 10TB used, then decrease as data usage rises.

What is interesting from a Flash developer's point of view is that Amazon's streaming server of choice which has been rolled out on a massive scale here is Flash Media Server. It should be noted that this service can only be used for on demand and live streaming, so allows no server side code or RTC based apps which include any server side logic.
You can find more info here.