Continuing its integration, Google+ Circles have been rolled out into Google chat services across all sites, including Gmail, iGoogle, the Google Talk client, and third-party apps.
Google Talk is a downloadable chat application that enables you to send instant messages, file transfers, and participate in video chats. Both Gmail and Google+ had the same email-based chat widget, which allows you to hold conversations with the people you contact the most through Google.
Previously you could only chat with someone if you knew his or her email address. Moving forward, anyone in your Circles – that has also added you to his or her Circles – will appear in Chat. Your Chat lists in other Google products will have all of your existing contacts in addition to the contacts added through Google+ Chat enabled Circles.
Once activated, you can choose to chat with anyone in your Circles, or you can customize it and only select specific groups of people. This can be managed through Privacy Settings
The chat list shows your most recent contacts, instead of a full list, and you can use the search box to find those that don’t appear. Google also noted that the contact relationships you had before you started using Chat enabled Circles are preserved and take priority. For example, if you blocked someone through Gmail, that person will continue to be blocked, regardless of if you add him or her to one of your Circles.
This is a minor update, but it shows that Google+ is continuing to move forward in its efforts to become the social layer for all Google sites.