+2  A: 

This looks like tabs but with some CSS to make it look different. http://jqueryui.com/demos/tabs/

Ryan Doherty
How can you make the movement smoothly and slowly?
Masi
Looks like a .scrollTo effect http://demos.flesler.com/jquery/scrollTo/
Ryan Doherty
+3  A: 

If you look at that page and view the source you can see exactly what they're doing. It's really only about 10 lines of javascript that scrolls to the section you want to sort when a link is clicked:

$.scrollTo("#answers-table", 400);

Then it calls the API using jQuery with the href supplied on the sort link:

var url = $(this).attr('href');
$.post(url, function(result) {/*function code is below*/})

Then the function that is specified for the callback replaces out the entire div you just scrolled to with the result:

var domelement = $(result);
$("#answers-table").html(domelement);

The actual tab styling is just specifying a different class for the link to change the color. This is also not exactly the order in which things are done but it's pretty close.

Someone please let me know if discussing the way StackOverflow's site works is against any sort of TOS.

Dave L
@Dave: Which tools do you use to analyse the site? Firebug or Google Grome?
Masi
I just used chrome, usually I use firebug but this was pretty straightforward so I didn't really need to debug it.
Dave L