progressive-enhancement

Jeff mentioned the concept of 'Progressive Enhancement' when talking about using JQuery to write stackoverflow. After a quick Google, I found a couple of high-level discussions about it. Can anyone recommend a good place to start as a programmer. Specifically, I have been writing web apps in PHP and would like to use YUI to improve the pages I am writing, but a lot of them seem very JavaScript based, with most of the donkey work being done using JavaScript. To me, that seems a bit overkill, since viewing the site without Javascript will probably break most of it. Anyone have some good places

I'm interested in using the JavaScript hashchange event to monitor changes in the URL's fragment identifier. I'm aware of Really Simple History and the jQuery plugins for this. However, I've reached the conclusion that in my particular project it's not really worth the added overhead of another JS file. What I would like to do instead is take the "progressive enhancement" route. That is, I want to test whether the hashchange event is supported by the visitor's browser, and write my code to use it if it's available, as an enhancement rather than a core feature. IE 8, Firefox 3.6, and Chrome 4.1