Peter-Paul Koch tests 19 different versions of WebKit/KHTML and creates a table comparing their successes and failures. His verdict: You’re going to have to test in multiple WebKit-based browsers for awhile, yet.
A plugin for Internet Explorer on Windows that aims to bring modern HTML5 capabilities to IE. I’m not sure exactly how much this will help web developers: One of the major sticking points that makes IE still so widely-used is that users in large organizations aren’t allowed to install things. Not even plugins.