It is possible to do what you are trying to do (Say things to a private group) on facebook even today but I don't know why they have made it so hard to use. I literally had to spend 15 minutes figuring it out and spend time to configure it.
But even with all that I am fairly confident that Google+ will fail to take off just like many of Google products lately. All they have introduced is a small set of features that facebook lacks. FB can add those in a matter of few months and then take out the whole reason for users to switch. Social networks are very very sticky.
well they are not as sticky as a super glue may be like a gluestick :) What I meant is that by virtue of being sticky, it gives FB enough time to attain feature parity with google+ thereby removing a reason for me to switch.
Unlike a search engine where the stickiness is just a habit.
If they feel threatened enough by Circles, I have no doubt that they will make it more visible, and available on all platforms.
That said, it's surprising how few people, even tech savvy ones seem to know about the functionality even though it's been around for ages. In fact, FB used to have a "how do you know this person" question when you added a friend, and they confirmed the relationship when they accepted, which is gone. It could be that they believe that most users don't want to segment their friends by categorizing them.
The iPhone client handles groups to an extent. You can pick one group to see a status update, but can't pick multiple groups, exclusions or custom on-the-fly groups
I wouldn't assume that it's so easy for Facebook to make fundamental changes to their friend system. It's woven into every other part of the site. The whole visibility thing would probably be a nightmare to implement.
Not only would it actually be challenging, but more likely than not Facebook would actually get hate for breaking the Facebook, just like every other time they've implemented any change more visible than an extra link somewhere.
But even with all that I am fairly confident that Google+ will fail to take off just like many of Google products lately. All they have introduced is a small set of features that facebook lacks. FB can add those in a matter of few months and then take out the whole reason for users to switch. Social networks are very very sticky.