Yes, Ke$ha I know … it keeps my engaged and is loud enough to block distractions when I code.

One thing that is clear and helped in making a design choice was the fact that the history api is not even close to being implemented in the IE family. This I doesn’t bother me too much since this is what you label as progressive enhancement but this limitation did make force me implement the pages in a way that it was working without it which is a good practice any ways this way it can work without javascript for example. I was lucky because the “page” area was well defined so I was able to create two endpoints in our rails stack where it switches between rendering a whole page and a partial depending on if the request is an xhr request or not … rails is good at that type of stuff.

Then for the history javascript example. I used the history.js library that offers some hashbang support as a html4 fallback. But you can use similar code for the native history api support with a few replacements

if( !History.enabled ) { return; } 

var loadPage = function( opts ) {
    if( opts ) {
        $.each( opts, function( k, v ) {
            defaultOptions[ k ] = v;
        } );
    }
    var panels = contentSpace.data( 'panels' ); 

    if(!panels[opts.path]) {
        $.get( opts.path, function( data ) {
            //cache page
            if( opts.page ) {
                panels[ opts.path ] = { 'data' : data, 'page' : opts.page };
                contentSpace.data( 'panels', panels );
            }
            contentSpace.html( data );
        });
    } else {
        contentSpace.html( panels[ opts.path ].data );
    }
} 

History.Adapter.bind( window, 'statechange', function(e) {
    var opts = { 'path' : History.getState().hash, 'page' : History.getState().data.page };
    loadPage( opts );
}); 

// hit it for the first time
History.pushState( optionHash, "Title", "the url path" );

This implementation is specific to fit the requirements I had but I wanted it to be out there in the interest of having more examples of how this can be implemented and demonstrate that it’s relatively straight forward. I sugar coded this with caching which will obviously prevent the users to see any “real” time info if there are any.

Good Links to explore HTML5 history api

• W3C spec
• The Awesome history.js library that makes this almost possible everywhere
• Mozilla Developer Docs
• Robert Nyman a swedish guy who works for mozilla who has an awesome website with bunch of examples