Google+ represents Google’s boldest step yet into the social networking space, with a direct shot across Facebook’s bow. After several failed social network projects (Buzz, Orkut, Wave), Google might have a winner with Google+, at a time when Facebook is due for a backlash.

There has been no shortage of coverage of Google+. If you want an overview, read this article or this one. In short, it’s Facebook, a place to post your thoughts and follow your friends, but with two things that set it apart in my mind:

1. Google+ has a streamlined design built on new technology. To my eyes, Facebook looks cluttered and unpleasant. Facebook keeps playing with the page layout, squeezing in chat columns on one side and more ads for more services on either side of the stream, and it’s not going well. At the moment, the Google+ layout is a breath of fresh air in comparison. Consider that to be trivial? Remember MySpace. If there’s any single thing that killed it, it was the way it became cluttered with crappy page layouts. Design matters.
2. Google+ came up with “Circles,” an intuitive, likable solution for the problem of sorting out “friends” and limiting posts to one group or another instead of making everything public. That has been the Achilles heel for Facebook: it just wasn’t built for a global audience of users, each one with hundreds of friends, leaving a public trail to be sniffed by employers and ex-girlfriends and bill collectors and everyone else on the planet. Facebook has no easy way to retrofit its service to accomplish what Google+ does brilliantly: choose an audience for a post and limit it to that audience.

Google+ has dozens of other features to set it apart, of course, many of them quite nice -group video chats, deep integration into all the other Google services, an interesting way to see posts about a particular topic (“Sparks”), clean well-designed mobile apps, and more.

A few months ago I started telling my children that Facebook was due for a pullback. I sense a fatigue around the privacy issues – not the day to day changes where this or that bit of info is exposed unexpectedly, but rather the flawed deep design of Facebook that causes everything to join a single public stream. The implications of that are too vast. It worked when college students were the only people using Facebook. It doesn’t work when your mom and dad are looking over your virtual shoulder. My bold prediction (before Google+ appeared, I promise) was that another service would come along that was designed to segregate friends into groups – and along the way, give people a chance to declare Facebook friend bankruptcy and start over, now that they know that it’s unworkable to follow a stream from seven hundred “friends.” (Not to mention a controversy that has yet to erupt about how Facebook decides behind the scenes which posts you will see. We’re due for a big public moaning about that.)

Nothing is going to displace Facebook completely but in only a few weeks Google+ has suggested there is room for more than one heavily used social network in the world, something a lot of people would have bet against. Google chose an interesting way to make Google+ exciting: it limited access for the first couple of weeks. Invitations were sent to early adopters, technical types, and media figures before the service was closed up under the “insane demand.” Nothing was better calculated to build demand than to make it unavailable.

The result is that Google+ had eighteen million users as of Tuesday, without any formal marketing whatsoever – no banner ads yet, no buttons to click on the Google search page, no bars across the top of YouTube begging everyone to join. Those things are all coming soon and the population of Google+ will swell astronomically when it does. Facebook has 750 million users. Google+ may or may not hit that number but it doesn’t need to, does it? The question is whether it will achieve a critical mass of people so that you feel you need to be there to see what your friends are doing. I bet it does.

No one has to jump on this right away. The service is new. Your friends aren’t there yet. Google is still sorting out the rules for participation by businesses and early adopters are figuring out how to manage circles. If you’re already a Facebook user, you’ll have to fight your inertia and your friends’ reluctance to switch to a different service.

If you’re curious and want to try it, let me give you three tips:

• For now, you can only join Google+ with a Gmail account. You may have a Google Account linked to your own email address but those accounts are not yet welcome to the Google+ party. It’s going to cause a lot of confusion if that’s not straightened out soon so that any Google Account can join. Right now it’s Gmail only.
• If you join and want some specific descriptions of the various parts of the service, this is as good a place as any to start. Here is an even more thorough guide.
• At the moment, invitations are open. Drop me a note and tell me your Gmail address. I’ll send an invitation if I can.