NetTuts.com has a new tutorial posted showing you some of the basics of uploading files via Ajax a bit more natively.

I can’t seem to reach the end of the fun stuff you can do with emerging web technologies. Today, I’m going to show you how to do something that—until the last while—has been almost unprecedented: uploading files via AJAX. Oh, sure, there have been hacks; but if you’re like me, and feel dirty every time you type iframe, you’re going to like this a lot.

Their method won't work in every browser, but it can be adapted to work as far back as IE6. The code and markup are included for each of the pieces for the example - the HTML for the upload form, the CSS to help style the resulting list of uploaded images, the simple PHP to handle the uploads and the jQuery-based code that implements the FileReader and FormData objects supported in newer browsers. The end result is a page like this that includes both the form and the list of uploaded images.