Google is adding the ability to ask personalised questions to retrieve information associated with your account directly from the search page, either by typing the command or by using voice search. Options include questions such as "What are my plans tomorrow?" and "Is my flight on time?"
Google already tracks much of this information via Google Now, but the option to search for the same details is useful. According to Google's blog post announcing the changes, these are some of the things you will eventually be able to get results for:
Flights: Ask Google "Is my flight on time?" to get info on your upcoming flights and live status on your current flights.
Reservations: Ask for "my reservations" to see your dining plans or "my hotel" to get your hotel name and address. With one tap, you can get driving or public transit directions straight there, saving you lots of steps.
Purchases: Ask for "my purchases", and you'll get the status of your current orders, so you know whether your mum's birthday present will arrive on time.
Plans: Ask Google "What are my plans for tomorrow?" to see a summary of upcoming flights, hotels, restaurant reservations, and events -- very useful when you're travelling.
Photos: Say "Show me my photos from Thailand" to see the photos you uploaded to Google+. You can also ask for "my photos of sunsets" if you want to show off the shots you've taken over the years -- Google will try to automatically recognise the type of photo you're asking for.
If you don't want to use the personalised results, you can disable them temporarily by clicking the globe icon above search results, or turn them off permanently by changing your search settings.
As with most Google Now options, it may be a while before we see this fully active in Australia. The initial roll-out is for US English users. Even without those options, Google's voice search is already an incredibly powerful tool.