The Social Network
Like all the other tech nerds seem to be doing lately, I too joined Google Plus, and third time does seem to be the charm. Google previously tried to conquer the social arena with Orkut and Buzz, and to some extent Wave, but they remained fringe products and were mostly forgotten. Plus finally has the necessary momentum behind it, and seems like it could be the next big thing.
Google should be damn happy about their success too - Facebook is clearly hitting Google where it hurts, that being the stream of ad money. In social media, people give their demographic information to advertisers on a silver platter. In contextual ads, the advertiser tries to react to what the user already wants - in social media ads, the advertiser can be much more proactive. Both kinds of advertising surely have their uses, but Facebook surely has shifted the balance of web ads. It's now advertisers pushing their products instead of clients looking for products to buy once again. Note that I don't have any hard statistics about what kind of ads really work the best on the web (I'd probably make a lot more money if I did), but the anecdotal evidence I have suggests that Facebook ads can be very effective. Now might be the last chance for Google to really strike back hard.
So, why is Google Plus any good anyway? There are a few things that strike me as pure genius:
1. Google has learned from other people's mistakes - the best kind of learning. It has privacy controls that people can understand, a clean user interface and it supports one-way friend relations. It does both short and long posts well. It has the potential to be the friends from Facebook, microblogging celebrities from Twitter and the professional atmosphere of LinkedIn all rolled into one.
2. It is an opportunity to start anew. Is your Facebook front page full of uninteresting crap from people you don't even really know like the cross-posting of this blog post? Now is the time to do the switch.
3. It has the power of the Google search engine behind it, with +1 buttons all over the search results. Also, +1 is so much better than like. Making "liking" the default way to relate to anything at all is a serious threat to human intelligence worldwide, whereas +1 is as neutral as you can get. And simple.
4. It doesn't try too hard. Google Plus is something that people already understand. XKCD said it the best:

It also struck me that "to circle" is a great way to say that you've circled someone in Google Plus - look, I'm using it already! It works in Finnish too: "piirittää". Over and out.
Update: And by the way, if you want a more far-reaching study of the future of social interaction, read Hannu Rajaniemi's The Quantum Thief - a story full of posthumans living in a moving city on Mars with an encrypted social network built right into their brain. It's not without its faults, but still the most eye-opening sci-fi novel I've read in a while.

Comments
I also find it interesting
I also find it interesting that Google gets much more from people than FB because G+ users explicitly create separate circles for different categories of acquaintances. Contrast with FB where everyone from co-workers to your best friends and family is just another friend. It's probably fairly difficult to get users users to classify people after-the-fact on FB, whereas with G+ it comes naturally.
Yeah, in G+ classifying
Yeah, in G+ classifying relations built right into the heart of the system like it should be. The FB version is just clunky, many people haven't probably even noticed it's there - and that goes for lots of other FB features too.