You no longer need an invitation. Although seriously if you hadn't already procured an invitation by now you probably had no interest in Google's Facebook challenger in the first place. And you may have had a point. After a lot of ballyhoo and folderol in the initial launch, G+ has become a bit of a ghost town and although Google issues no numbers on the service, independent analytics have suggested a significant drop in visits and updates.
Some new features were also added.
For those into Google+'s Hangouts, you'll now be able to participate in them on your cellphone, if your phone is an Android 2.3+ device with a front-facing camera, though Google promises iOS support is coming soon. Additionally, they've added a feature called Hangouts on Air, which isn't a "hangout" at all so much as it is a broadcast meant for a larger audience, with a limited number of "broadcasters" enabled to start with (and we're willing to bet that one of those lucky few will be Robert Scoble, an avid Google+ user). Hangouts have also gotten a few other extra useful features such as screensharing, a sketchpad for doodling, Google Docs support, and the ability to name Hangouts.