First off, you realize that there's a Google Plus iPhone app already submitted by Google and coming to the iPhone in the very near future. Could be as soon as by the time you read this post. Still, it's nice to know that there's a mobile interface because it works even if you don't have an iPhone or prefer not downloading applications for your phone. Why you wouldn't want to put apps on your phone, I don't know, but that's another story. :-)

The best thing about Google Plus in my opinion is what I call the asymmetric friend model, so someone can add me to one of their Circles and I have no obligation to return the favor and add them to any of my own Circles. In fact, about 20% of the people who are adding me to their Circles aren't ending up in my own Circles: I'm waiting for an AskDaveTaylor G+ page to have them connect instead.

But back to the topic at hand!

On your iPhone, when you get a new person adding you to one of their Circles, here's what you see in your home page:

Tap on "Notifications" and it'll show you what's been going on with your account. As you can see, I have a fair amount going on:

I'm going to reciprocate the connection that my friend and colleague Joe Pezillo made with me here in G+ so I'm going to tap on his name in this display:

if you guessed that I should tap on "Add to Circles", you're exactly correct. I tap on that just below his name and it shows me all the different Circles I have created:

He's a friend, so I'm going to tap on "Friends" then tap on the "Done" button on the top right. A split second later and...

As you can see, Joe is now in one of my Circles too and if I tap on "1 Circle" I'll be reminded that he's a Friend. Works for me!

Note that you can also add people to more than one Circle, so you could have Friends, Colleagues and College Chums and potentially add someone to all three. Slick.