There is a list of all your circles on the left. Clicking on any circle will only show you posts from the people in those circles.

As is said in the article, posts from people who added you but you didn’t add won’t show up in your stream but you can get to them easily if you want to.

There are ways to improve this. At the moment you can only display one circle at a time. It would be nice if you could select more than one circle at once. Also, Google+ defaults to showing you all circles when you load it up and there is no way to change that. It might be nice to be able to only display posts from people in certain circles by default.

But I think that’s some fairly capable filtering, at least if you manage your circles right.

Circls is a two-way limiter of data input. The sharer limits a post to some circles, and the receiver only sees the post in a circle in which the sharer is in. This two-part filter is what Google is betting on is enough to sort the stream.

Also important: Google is really good at sifting through a big mass of information presenting you the relevant stuff. This in itself is enough that they have an edge in my opinion.

As the other commenter said you can just click on a circle to see shares only from those people. Also, the shares from the people that have added you to their circles appear in Incoming (there's also a link at the top of the stream for Incoming)

the linked article specifically addresses this. you should read it.

You are on one of the best connected communities, want an invite to G+ and haven't put your email in your profile?

And no there isn't any good way to do that, yet.

I have an email in my profile, but no Google+ invite :(

FYI, your email needs to be in the 'about'-section for others to see it. the 'email'-field is not public.

Good point. I added an email to my profile but I am still reluctant to spam every G+ submission with pleas for an invite.