Last year I was looking at some options for making SharePoint content available for a wide range of audience around the world if and when it comes under a DoS attack. We were looking at Content Delivery Networks as an option. CDNs can improve performance and availability. But, with sophisticated apps used on the WWW, it is not just the raw content that needs to be available but also the functionality. I think this is where developers need to take care that the code written can work effectively with a CDN. I think the Ajax CDN plays a vital role here: http://www.asp.net/ajaxlibrary/cdn.ashx.
Everything going onto the Cloud these days can we safely assume that our provider will also give us these capabilities of a CDN? Azure does it.