If you've already been on Plus, and you're in chrome or (I think) Firefox, it won't do a search when you type "plus" as the top autocomplete suggestion will be

If you've already been on Plus, and you're in chrome or (I think) Firefox, it won't do a search when you type "plus" as the top autocomplete suggestion will be "http://plus.google.com http://plus.google.com. To search, you'd have to key down the list of suggestions.