Google Now is a feature of the new Jelly Bean update to the Android operating system, available on tablets and phones that run Android Jelly Bean. It's either creepy proof that Google knows entirely too much about you or progress towards an even better user experience. Take your pick, and turn it off if you find it creepy.
Google Now Is Optional
Whenever Google starts to step into "Oh my gosh, Google is just spying on me!" territory with a project like this, it's important to remember that this is an optional feature designed around your convenience. Just like you don't have to log into Google to use the search engine, and you can opt out of saving your search history, you don't have to turn on Google Now. It's off by default, and Google will prompt you to take an action to turn it on if you want to use it. It's also a work in progress. Key Lime Pie or whatever the next version of Android is named will undoubtedly have an even more refined version of the service.
In order for some of these features to work, you also have to enable Web history and location services. In other words, you're opting in to give Google a lot of personal information about your searches and your location. If you're not comfortable with the thought, just leave Google Now off.
What Does Google Now Do?
Weather, sports, traffic. Google is like a (very quiet) personal radio station. Google Now is designed to provide you with useful information in "cards" that you'll generally see as either notifications or when you launch Chrome on your Android device. Currently there are only ten cards, but Google is working on adding more. The cards that show up as notifications are for items that are time dependent, such as events and your work commute.
Weather - Every morning, Google tells you the local weather forecast for your home and work. Probably the most useful card in the set. This only works if your location is on.
Sports - Since I'm not a big sports fan, this card hasn't shown up for me. However, if you've searched for scores for specific teams and have your Web History enabled, Google will just automatically show you cards with the current scores to save you the frequent searches. Ok, this card might come up for me if my home team makes the Final Four again.
Traffic - This card is designed to show you what the traffic is like on your way to and from work or your next destination. How does Google know where you work? Good guesses. It uses your recent searches, your default map location if you've set it, and your common location patterns. It's not hard to figure out that the location you typically spend 40 hours a week in is your work location, for instance. In my experience, the guesses are a combination of very accurate (where I work and home) and wild guesses based on the last place I searched, such as directions to the nearest Best Buy based on an earlier search about the price of electronics.
Public Transit - This card is designed so that if you step on a subway platform, you see the schedule of the next trains leaving the station. It doesn't work with my park and ride stop, so I haven't had a chance to check this feature yet. It seems like it would be extremely useful for commuters or even for those times when you visit a city and aren't quite sure how to use the public transport.
Next Appointment - If you've got a Calendar event, Google combines this with the Traffic card for an appointment card with driving directions. You'll also see a notification on when you should leave to get there with traffic conditions. It makes it pretty handy to just tap and launch Map directions.
Places - If you're away from your work or home location, Google might suggest nearby restaurants or points of interest. This is on the assumption that if you're downtown, you're probably out for a beer or want to grab a bite to eat.
Flights - This is designed to show you your flight status and schedule and give you one-tap navigation directions to get to the airport. This is, like the Traffic card, based on a good guess. You have to have been searching for that flight information for Google to know you're on that flight. Otherwise, no card for you.
Translation - This card is supposed to suggest vocabulary words when you're in another country. I haven't traveled overseas since the Jelly Bean update, so I haven't had a chance to try it out.
Currency - This is just like the Translation card, only with money. If you're in another country, you see the current conversion rate.
Search History - Google doesn't list this as one of their initial cards, but it seems to serve up a card with nothing but several recent searches. I could then click on the searches to open them in Chrome on my phone or tablet.