If you've been dutifully checking your mobile app updates (you do check, right?), you may have noticed a Google+ upgrade slip through largely unannounced. That revision might be bigger than you think -- although its exact value depends entirely on the platform you're running. If you're an iOS user, you now have the choice to open web links in Chrome for iOS instead of Safari; it's not the same as changing the default browser, but it will keep Google fans firmly ensconced in their preferred ecosystem while they're using Apple devices. On the Android side, it's now possible to watch live Hangouts On Air sessions if friends aren't ready and waiting for a chat. Both versions now let teens join any kind of Hangout, and there's a raft of tweaks on either side of the fence. If you've been waiting for either of the two major features to jump in, the app downloads are waiting at the source links.