For more, including how to get started, keep reading.
To get started, visit groups.google.com. Name your group, give it its own email and web addresses, and choose your level of privacy. Groups can be public, announcement-only (anyone can read posts, but only group members can post), and private — meaning all content is limited to the group only. You can browse existing groups by category, and even join them yourself.
Google Groups has been around for a while and is similar to Facebook Groups in that it allows you to quickly share information with a select group of people. While no plans for the recent acquisition of mobile group messaging service Disco have been announced, I predict Google plans to integrate the service with its Groups functionality for a full experience. As a huge fan of Facebook Groups I haven't played around with Google's similar service much, but plan to keep an eye on it as it evolves.