V!NCENT writes with an excerpt from a new publication by Microsoft: "As web sites evolved into dynamic web applications composing content from various web sites, browsers have become multi-principal operating environments with resources shared among mutually distrusting web site principals. Nevertheless, no existing browsers, including new architectures like IE 8, Google Chrome, and OP, have a multi-principal operating system construction that gives a browser-based OS the exclusive control to manage the protection of all system resources among web site principals. In this paper, we introduce Gazelle, a secure web browser constructed as a multi-principal OS. Gazelle's Browser Kernel is an operating system that exclusively manages resource protection and sharing across web site principals." Here's the full research paper (PDF).