These browser transport methods are being exploited to include or link to base64 encoded images. Some of the methods being developed are trying to replace image calls in css sprites. The concept is that an embeded base64 image would be more accessible. Others, like the guys at cappuccino.org, are trying to achieve single files that combine css/images/JavaScript inside JavaScript. The purpose is highly compressed, both minified and gzipped, JavaScript files that save bandwidth. These could then be distributed and cached nicely among CDNs.

These methods are great in theory, but concern me when it comes to graceful degradation, accessibility, and availability. How would users without JavaScript, MHTML, or Data URL protocols view these dependent websites… More to come.