"Instant Preview" has to be the single worst change that google ever made to their search pages. I'm at the verge of switching to bing for a while because I keep triggering these god-awful popups by accident.

Bing has hover previews too, they just activate with a gesture to the right rather than a mouseover. The content of Google's previews is far superior though.

You can turn instant preview off: http://www.google.com/preferences

I think you are confusing "instant preview" with "Google Instant" search

You might be right, though I have a feeling I might be part of one of those "1% experiments" that Google is known for. Right now I have Instant Search off, and it also keeps thumbnails for showing up for search results. However, I turned Instant back on, and the thumbnails still don't show up (at least not automatically). I guess YMMV... sorry for the misleading info.

Do you have an option for that on your preferences page?

Serious question, because I don't.

Whenever I read stuff like this, it's painfully obvious that browsers were not designed as the universal application runtime.

Why are we using technologies designed for displaying documents to write applications? Because they're there, I suppose.

It's interesting that the previews are made available using JSONP. This should technically allow other web sites to also retrieve and display them.

The post doesn't mention whether Google allows this, though, or whether they expect the interface to remain stable.

Ok, but didn't have the one piece of information I was hoping to learn. Does anyone know what Google is using to render the preview images?

Now that these images are in search results, everyone will need to make sure that Google renders their site well.

Since Google also does a browser I'd imagine it's a cut-down version of Chrome's renderer.