[henrikschroder]

Turning

  <div>
      <h1>Hendershot's Coffee Bar</h1>
      <p>1560 Oglethorpe Ave, Athens, GA</p>
  </div>

Into

  <div itemscope itemtype="http://data-vocabulary.org/Organization">
      <h1 itemprop="name">Hendershot's Coffee Bar</h1>
      <p itemprop="address" itemscope itemtype="http://data-vocabulary.org/Address">
        <span itemprop="street-address">1560 Oglethorpe Ave</span>,
        <span itemprop="locality">Athens</span>,
        <span itemprop="region">GA</span>.
      </p>
  </div>

...is not markup pollution? It's three times as big as before, and the value of this is still questionable.

[what]

But it's smaller than the proposed data island.

   <script data>
   bizcard={
     name: 'Hendershot's Coffee Bar',
     address  :{
       line   :'1560 Oglethorpe Ave',
       city   :'Athens',
       state  :'GA',
       zipcode:'30606',
       country:'US'
     }
   };
   </script>

   <div>
      <h3><span data="bizcard.fname"></span></h1>
      <span data="bizcard.address.line"></span>
      <span data="bizcard.address.city"></span>
      <span data="bizcard.address.state"></span>
   </div>

Which also won't work for people with javascript disabled. Plus, does Google go through your javascript and figure out what eventually makes it onto the page?

[Kilimanjaro]

Well, templates is another issue, mixed with data island may make it more verbose.

The idea of the data island is to have the data separated from the content and let consumers use the data whenever they need it. I am now studying the possibility to use a link tag and have the data island external, like rss/atom to save bandwidth when 90% of consumers won't care about the data. And for those who care, they just load the external link and there you have it, all the data without scraping.

[jarin]

Google doesn't load JavaScript, that's why they have the AJAX crawling URL scheme: http://code.google.com/web/ajaxcrawling/docs/getting-started...

They're the URLs you see on Facebook that have #! in them.

[jacobolus]

It’s mostly intended for places where data is going to be slurped out of a database and dumped into a template or renderer. Adding a bit of extra gunk to the template isn’t the end of the world (especially if you have a sane template system).

If I’m writing some text by hand, I’m going to use markdown and just write:

    # Hendershot’s Coffee Bar
    1560 Oglethorpe Ave, Athens, GA

As for the benefits: having some widely-used machine-readable metadata linked directly to the data could let browsers do some pretty neat stuff in the future, like letting a user click to add an event to his calendar, look up directions to an address, or add a person to his contact book.

[dctoedt]

Kilimanjaro's JSON data-island example is certainly more readable. OTOH, with that approach there's the risk that, during maintenance, the data island will be overlooked and will become inconsistent with the human-readable information.

Edit: Perhaps that risk could be mitigated by having the human-readable markup issue a JS call to the data island, which would have the benefit of being DRY-compliant.