When viewing iGoogle, each section is able to be drag-and-dropped to anywhere else on the page and then the state of the page is saved. I am curious on how this is done as I would like to provide this functionality as part of a proof of concept?
UPDATE
How do you make it so that the layout you changed to is saved for the next load? I am going to guess this is some sort of cookie?
Any up-to-date client side framework will give that kind of functionality.
Just to name a few...
Regarding the "saving" (persistency, if you will) of the data, this depends on the back-end of your site, but this is usually done via an asynchronous call to the server which saves the state to a DB (usually).