Google Now is the search engine of tomorrow, or the Google of tomorrow rather. The search engine won't just serve 10 links and call it a day, it will be able to answer your every question.
Google Search already does that to a degree, you get whether info, flight details and currency conversion without leaving the site.
But Google Now goes beyond that by providing you with more direct answers for more types of queries and by even anticipating the things you will look for and providing you with info before you even ask for it.
This is what Google aims to do with the regular Google Search as well, it has been running an experiment which provides you with answers for more of your searches and for things you wouldn't necessarily use Google Search for, like looking for a restaurant reservation you made.
Google is now expanding the experiment and tweaking some of the features based on feedback. Note that you still have to enable it manually if you want to join.
"Instead of digging through your email, you can find a lot more useful information from your Gmail when you search on Google.com," Google explained.
"For example, in addition to searching for [my flights], you can now search for [my purchases] to see a list of recent online purchases from select merchants and track the packages to see if they’ve arrived yet," it added.
The end results are answers to more of your questions straight from Google, which can only be a good thing. And, as Google becomes better at understanding context you'll not only get better general results, via the knowledge graph, you'll also get better personal results, things like appointments, gift suggestions and so on, the possibilities are limitless.