Start G+ is an extension for Google Chrome that does many things at once. One among this is it automatically cross posts whatever you share on Google+ to both Twitter and Facebook.
Before you can start cross posting you have to connect your Twitter and Facebook account to Start G+. You can do this from Start G+ button on the black Google navigation bar at the top. Once this is completed, open Google+’s sharing form and you should see a Facebook and Twitter icon underneath to indicate that your post will be shared to those social networks as well. To turn off sharing simply click the icons once.
Aside from sharing stuff, Start G+ also brings your Twitter and Facebook stream and intertwines them with your Google+ stream so that all updates are visible on a single stream on Google+. There is an option to turn this off. The Google+Facebook extension does it better, in my opinion.
Start G+ also adds a Gmail inbox notifier to the top bar. It displays a small icon with a number indicating the number of unread messages in your inbox. Clicking on the Gmail icon shows a menu with the unread messages that let you access your emails directly inside Google+. Not bad, huh?