It's been one of the most requested features since Google+ launched back in June - users want to be able to share their custom-built Circles of users with each other. And as of today, the feature is here. Just click "Share" next to the Circle in question and you're off and running.
And why would you want to share a Google+ Circle? Any number of reasons: if you want to share your carefully curated list of Internet celebrities, ace photographers, or, say, ZDNet reporters with friends. Similarly, if a friend or coworker has just joined up with the Google+ social network, it can be useful for sharing the list of mutual acquaintances.
The feature was officially announced in a video by Google+ engineer Owen Prater, who explained that "when your friends receive your circle, they can then pick and choose who to add to their own circles." Any changes made to that circle stay unique to you, and you can set your own comment when you share, meaning you don't have to share the name of that Circle with anyone.
This isn't a true Facebook-style "Groups" feature, but Google+ circle sharing is certainly more privacy-minded, giving a finer control over what you choose to reveal when taking advantage of the new feature. It's a smart move, given the discussions that ensued over the first iteration of Google+ cross-circle content sharing.
It certainly sounds like Google is trying to speed up the Google+ development and feature release cycle now that it's out of field test and open to all. Feel free to discuss what Google's social platform is still missing in the comments below.