Oh, wow, pretty impressive. Tweets show up on Google as soon as you hit the "post" button (see the official announcement). I tried searching for a client brand, and sure enough, a scrolling stream of tweets containing the brand name showed up on the first page of results.
Is ranking on the first page that easy now?
How long till the first Twitterbomb -- tricky twittering for the sake of landing (and staying) on the first page for a search term?