You could also mention that you can select all elements of a widget using the :data selector, that's usually more useful then the is check.

Tough I wonder if we actually want to document this (at least in this detail) if we're going to land that instance method?

PS: There are two double spaces in the first p element.

$( "#elem" ).data( "ui-progressbar" ); would become $( "elem" ).progressbar( "instance" );

But wouldn't you still need the :data selector for determining whether the current element is a widget and to get all widgets on a page?

Yes, you'll still need the :data selector to find all instances. And we want to document this today (and probably even backport it to the 1.9 docs.

I think what users are really looking for though is documentation on each widget page, which can be done with an include. We'll still want these docs for the jQuery.widget entry, of course.

Updates made.

I can tackle adding something to the individual widget's pages next, but for now any concerns landing this? @scottgonzalez @jzaefferer

Looks good to me. Just update that href to have the slash.