Nathan Weinberg reports that Googlers Advised To Limit Choice by professor Barry Schwartz, not me - the other one who has his fame from teaching and publishing on psychology, and wrote the very popular Paradox of Choice.
Nathan posted his presentation, where he urges Google to limit the choices available to the Google searchers. I did not have time to watch the hour long presentation, but I imagine this is kind of like the "invisible tabs" approach. So limit the options, and you can give the user more by doing so - "more is less."
Forum discussion at Search Engine Roundtable Forums.