Michal Zalewski from google has published an an extremely in depth guide describing the various behavioral differences between the major browsers.

"I am happy to announce the availability of our "Browser Security Handbook"
- a comprehensive, 60-page document meant to provide web application
developers and information security researchers with a one-stop reference
to several hundred key security properties and sometimes counterintuitive
quirks in contemporary web browsers:

http://code.google.com/p/browsersec/wiki/Main

Having a clear picture of these characteristics appears to be of
significance to building secure web applications, and to auditing existing
designs for potential weaknesses. For this reason, I am hoping that the
document is a valuable contribution to the information security community.

BSH currently covers recent releases of Microsoft Internet Explorer
(versions 6 and 7), Mozilla Firefox (versions 2 and 3), Apple Safari,
Opera, Google Chrome, Android embedded browser, and a handful of browser
plugins.

Please note that due to the sheer number of characteristics covered, I
fully expect some kinks to show up here and there; feedback from vendors
and security researchers is greatly appreciated."