Google is building support for OS X's Notification Center into Chrome, meaning that the browser's own pop-ups could be going away on the Mac. Chrome has supported notifications for a few years, but they've always been done entirely through the browser, with a big ugly box popping up anytime it went to alert you. Now, Google says it's looking into using OS X's native notifications.
You can try it in Chrome's latest release
Google hasn't fully committed to making the switch just yet, but initial support for native notifications is already built into Chrome as an experimental feature. You can enable it by going to "about:flags" in the address bar, and then looking for "enable native notifications."
Any Mac user who regularly receives push notifications through Chrome should be happy to hear this. Chrome's own notifications are clunky and irritating. If Chrome's window is hidden, for instance, a notification will bring it back on screen in front of everything else. Its notifications can also pop up on one workspace, and then drag you over to a different workspace where Chrome is located. Obviously these aren't the worst things in the world, but it's a repeated annoyance, and it sounds like Google is doing away with it.