Google also sort of had to make this move, with Facebook being very quick to implement more and more features seen in Google+.
At the same time, Google also announced a lot more. Here's a quick overview of what I found particularly interesting.
After they recently opened their read-only API to public posts, outcry was loud for more API's. Earlier today I noticed that I could enable something in the Google API Console called Google+ Hangouts API - but with no accompanying information page to it.
Today they released the +Hangouts API which allows developers to add apps to the hangout experience. Demos include a simple "Yes, no, maybe", but possibilities are endless. I'm mainly thinking in terms of better face-to-face remote collaboration tools. But who knows what other people think about?
Oh, and hangout goes mobile too! And adds screensharing. And Google Docs next to a hangout. And doodling in a hangout. And named hangouts. And... oh, I think I got through the list now.
It took some time, but we can finally search through public stream posts. Queries can be saved and basically turn in to sparks. Nice+! The experience isn't quite as optmized as we know it from Google (web) Search - results include full posts and search words are not highlighted - but knowing Google things only get better over time.
As mentioned, everyone can now join Google+
... still missing
Even though Google+ is completely open to everyone now, there are still a few things missing. Most significantly the ability to use it with a Google account connected to a Google Apps domain, and a business pages concept. It is my expectation (and hope) that those will be very much connected. Think circles based on domain, and business-wide messaging. Not too long, sub-organizations got added to Google Apps and I can only assume that this will have some effect on the soon-to-be-launched Google +Apps experience.
Also on my wishlist: Private messaging (or perhaps Huddle in the desktop browser), nearby-stream in the desktop browser, private reply to posts.
Did I hear anybody say that it looks more and more like Google+ is just an implementation of Google Wave with a lot better UI?