The official description from that site:

Google Instant is a new search enhancement that shows results as you type. We are pushing the limits of our technology and infrastructure to help you get better search results, faster. Our key technical insight was that people type slowly, but read quickly, typically taking 300 milliseconds between keystrokes, but only 30 milliseconds (a tenth of the time!) to glance at another part of the page. This means that you can scan a results page while you type.

The most obvious change is that you get to the right content much faster than before because you don’t have to finish typing your full search term, or even press “search.” Another shift is that seeing results as you type helps you formulate a better search term by providing instant feedback. You can now adapt your search on the fly until the results match exactly what you want. In time, we may wonder how search ever worked in any other way.

It’s starting out only in the US, UK, France, Germany, Italy, Spain, and Russia. It is compatible with Chrome v5/6, Firefox v3, Safari v5 for Mac and Internet Explorer v8.

Mayer finally announced the feature. The official blog post for it is up now too.

It has a scroll to search feature that lets you scroll through predictions and see results instantly for each as you scroll down.

Mayer says its not “search as you type”. It’s actually “search before you type” because it’s predicting results. “There’s even a psychic element to it,” she says. She recalls an old Google April Fools day joke about a similar product.

Google Instant will be rolling out over the course of today in the U.S. Over the next week, the other countries mentioned will start getting it (for users signed in).

The Google Instant team says its great for weather, because you can just press “w” to get local weather results.

“It’s possible that this feature may increase or decrease your overall impression levels,” says Google’s Dan Friedman. “However, Google Instant may ultimately improve the quality of your clicks since it helps users type queries that more directly connect them with the answers they need.”

There is also a post on Google’s Webmaster Central blog, which webmasters should read. Impressions are measured in three ways, it says: the traditional way, when a user clicks on a link that appears as they begin to type, and when a user stops typing, and the results are displayed for a minimum of 3 seconds.

During the presentation, Google says Google Instant will “enrich your life” and help you learn more while you search. They say it will seem so obvious in retrospect.

I must have missed this in the announcement, but Google will reportedly hide explicit search results in instant results.

Google is working on implementing the feature in browser search boxes (possibly in the next few months).

AndroidGuys points to a way you can use Google Instant on mobile already (as opposed to waiting a few months). Hat tip to Michael Martin for that.

Original Article: Google’s event is about to happen, but the company has already uploaded the following videos of the product: Google Instant. The videos confirm speculation about the announcements being based on “streaming search results”.

Here’s another video Google has uploaded about the testers:

And yet another video Google has uploaded:

The company said they would only be used in place of some URLs, mainly ones that don’t give the added context of a link the way that breadcrumbs do. Interestingly, there seems to be an incentive for those who go the breadcrumb route because of the multiple links that you just don’t get with regular search results.

Google’s move was generally well received. For example, a commenter going by the handle Stupidscript said, “It’s definitely a good time to start wrapping your head around the notion of ‘providing context’, because the web is heading into its “semantic” period … where each link will be more or less valuable based on its relationships with and context to information found behind other links.”

Google’s use of breadcrumbs in search results is the focus of a recently submitted question to the Google Webmaster Central team. The question was, “Google is showing breadcrumb URLs in SERPs now. Does the kind of delimiter matter? Is there any best practice? What character to use is best? > or | or / or???” Google’s Matt Cutts responded:

Matt says you should have a set of delimited links on your site that accurately reflect your site’s hierarchy. He also notes, however, that it is still in the “early days” for breadcrumbs.

“Think about the situation with sitelinks,” he says. “Whenever we started out with sitelinks, it took a while before…for example, we added the ability in Google Webmaster Tools where you could remove a sitelink that you didn’t like or that you thought was bad. So we started out, and we did a lot of experiments, and we’ve changed the way that sitelinks look several times. And we have different types of sitelinks (within a page, and the standard ones you’re familiar with). So we’ve iterated over time.”

In this same way, he says, Google is in the early stage with breadcrumbs and he has seen different experiments with them. For example, there have been prototypes where the breadcrumbs were in the rich snippet gray line, above the regular snippet. “Having it in the URL is kind of nice, but it could still change over time,” he says.

He says the best advice he can give is to make sure you have a set of delimited links that accurately reflect your site’s hierarchy, and that will give you the best chance of getting breadcrumbs to show up in Google, but Google will continue to work on ways to improve breadcrumbs. He says any new announcements about it will likely be made on the Google Webmaster blog.

While Matt doesn’t exactly lean toward one way or another with regards to which character to use as asked about in the submitted question, all of the examples I have seen highlighted show the “>” used. That includes examples from Google’s original announcement on the inclusion of breadcrumbs (if you see other ways, please point them out in the comments). Based on that, if I were going to choose one, I’d go with that.