<p>Jeff mentioned the concept of 'Progressive Enhancement' when talking about using JQuery to write stackoverflow.</p>

<p>After a quick Google, I found a couple of high-level discussions about it.</p>

<p>Can anyone recommend a good place to start as a programmer.</p>

<p>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.</p>

<p>Anyone have some good places to start using this idea, I don't really care about the language.</p>

<p>Ideally, I would like to see how you start creating the static HTML first, and then adding the YUI (or whatever Ajax framework) to it so that you get the benefits of a richer client?</p>

As you've said
To me, that seems a bit overkill, since viewing the site without Javascript will probably break most of it.
This isn't progressive enhancement. Progressive enhancement is when the site works perfectly without JavaScript or CSS, and
then
adding (layering) these extra technologies/code to increase the usability and functionality of the website.
The best example I can give is the tag input box on this website. With JavaScript turned off, it would still work allowing you to enter tags separated with a space. With JavaScript turned on, you get a drop down with suggestions of previous entries.
This is progressive enhancement.