Update: New ignore option to hide people on Google+ [Google Plus]

Ignoring people

When a person adds you to a circle, you might not be interested in what they have say, but blocking them may seem too harsh. Instead, you can ignore them, which will limit what they can share with you.
You can ignore someone from the following places:

• The notifications in your Google+ bar
• Your Incoming stream
• Under the 'People who have added you' tab while editing your circles

When you ignore a person:

• They'll be removed from the list of ‘People who have added you.’
• New content will no longer be delivered to your Incoming stream, and content they've already shared will be removed from Incoming.
• Their mentions of you won't appear in your stream and you won't receive a notification for them.

To access the list of all of the people you’ve ignored, click the Circles icon at the top of the stream, click More actions, and select View ignored. If you decide to add a person you previously ignored to a circle, that person will be removed from the list.
Keep in mind that ignoring someone is not the same as blocking. An ignored person will still be able to comment on your public posts, tag you in photos, and add you to circles. You'll still receive notifications when an ignored person tags you in a photo. In addition, people you’ve ignored may appear as a suggestion again at a later time.
If you want to further limit interaction with someone, consider blocking them instead.