I'm all for opening up oneboxing, but not for creating yet another standard.

There are already several competing standards for onebox-like functionality and semantic representation of web page data:

* [oEmbed](http://oembed.com)
* Facebook's [Open Graph](http://ogp.me)<sup>1</sup>
* [Microformats](http://microformats.org)
* [Schema](http://schema.org)
* [RDFa](https://en.wikipedia.org/wiki/RDFa)

If Stack Exchange is going to do this, they should adopt one of those instead of re-inventing the wheel. My preference is for oEmbed, with a secondary preference of Open Graph.

[![Fortunately, the charging one has been solved now that we've all standardized on mini-USB. Or is it micro-USB? Shoot.][1]](http://xkcd.com/927/)

<sup>Note 1: what you're proposing is pretty close to Open Graph anyway.</sup>

  [1]: http://i.stack.imgur.com/rqCuz.png
  [2]: http://i.stack.imgur.com/1cLhd.png