updated 04:15 pm EST, Thu January 26, 2012
Social networking now available to 13-17 year-olds
Google has opened up Google+ to teens 13 and older. Previously, only adults over 18 could participate in the service. Google has also implemented safeguards to help make sure the younger crowd's participation in the social network is safer until they're adults.
Google+ lets individuals share information either within their private circles or push it out publicly to a global audience. When teens attempt to publish something to more than just their friends, a pop-up appears, asking them if they're sure they want to make it completely public.
Google is also protecting teens from random strangers contacting them. By default, Google+ only lets individuals within the teen's circles contact them. If someone outside their circle tries to contact them, the teen is notified, and they do have the option of manually enabling communications.
The same applies if someone outside their circles tries to join a Google+ hangout. In such a situation, the teen is temporarily bounced from the hangout. They can rejoin manually after a brief wait.
The new policy of 13+ brings participation in line with Google's practice of letting anyone that age create a Google Account in most countries. Google may also be counting on encouraging adoption for a younger crowd that hasn't yet established itself in Facebook.