Microsoft just announced the AJAX CDN (Content Delivery Network). The CDN was made available to aid in the serving of jQuery and ASP.NET AJAX script libraries to the end user. Traditionally, these files are served from the same server that is serving the web site content.
The CDN uses edge-caching to deliver this content instead. Microsoft’s edge-cache servers are strategically located all over the world. This has a couple of advantages. First, it’s faster because the data is coming from the server that is closest to the end users locale. Second, if the end user has already visited a site using the CDN, this information is probably already cached locally.
Also remember, without the CDN this information is downloaded every time a user visits a unique AJAX enabled site. Even if the applications are the same, the fact that they are located on different systems causes the information to be re-downloaded. But with the CDN, since it distributes files from one common location, it is very likely that some other end user has already downloaded the file in question while visiting a different site, so that should make things faster.
Personally, I think the drawbacks are minimal, however I felt they were still worth including.
For additional information about the AJAX CDN and how to implement it, head over to the Scott Guthrie’s blog.