Google announced at the Google I/O 2014 that it would be bringing in several new features to Chromecast in order to make it more useful. Google had also opened SDKs of Chromecast in the recent past to the developers in order to encourage them to add value to the internet streaming device. While at I/O Google did not really say anything about the capability of playing local videos via Chromecast, it did introduce the next best thing, and that was the ability to mirror or cast your screen from the tablet or mobile device.
Google had said that the feature will be made available in summer, and sure as they say, Google has stuck to its word and has rolled the update out. You will need to update to the latest version of Chromecast on your Android device to be able to wirelessly cast or mirror your display on the TV over Wifi. This means you can mirror everything from your device, right from pictures, videos to applications to the larger screen.
This would mean, that you can use Chromecast as a substitute to projectors as you can simply plug it in to a large screen in case you want to give a presentation right out of your Android device. However, this feature will be available only on selected Android devices for now. It would be rolled out in time to other devices, but for the moment only the high end HTC, Samsung and Nexus devices will see this option in the settings of the application.