Google Suggest FAQ

Google Labs

Completes words in a drop-down list of ten possible &/or likely ways to complete any word you begin to type in the search box AND how many times that option is searched at Google

Main features from FAQ

1) Works in real time
2) Algorithms use a wide range of information to predict the queries - give Google Zeitgeist as an example data source
3) Does not base its suggestions on your personal search history
4) Suggests more refined searches up front - less need to refine queries
5) Uses information about the relative popularity of common searches to rank its suggestions

Labs preferred example searches:

You type a few letters and Google Suggest might offer:
"bass" "bass guitar" "bass fishing"
"prog" "programming" "programming languages" "progesterone" "progressive"
"duke" "duke university" "dukes of hazzard" "duke nukem" "duke ellington" "duke power"

The implications for SEO are discussed at Webmaster World
where AaronL points out the differences between "did you mean" and the new suggest feature:

"The "did you mean" feature offers suggestions after you submit your query, thus allowing you to finish your thought. In addition, it is used most often to address spelling issues, rather than completely different search strings. Here G has the opportunity to shape the query and “herd” the user down G's preferred path."

The last sentence sums up the general feeling about the effect "suggest" could have on searchers habits if it is integrated into the main search.

Alphabetical advantages become interesting again
strong adult filter is on
New opportunities to spam google: how do I get to the top of the suggestions list?

internetheaven believes that "This means that all traffic will be directed to a few specific terms, obviously the traffic for these sites will increase dramatically while the others disappear off the face of the earth. Now you don't have to work out which terms users want, you have to work out what Google is going to recommend they want .... "

While Tigrou feels that from a searchers point of view it "Seems to be a terrible example of engineers gone wild & somehow bypassing look/feel & usability people."

The Google employee who came up with the idea in their 20% time posts in the Google Blog This "Labs project that provides you with search suggestions, in real time, while you type. We've found that Google Suggest not only makes it easier to type in your favorite searches (let's face it -- we're all a little lazy), but also gives you a playground to explore what others are searching about, and learn about things you haven't dreamt of."