• by Laurie Sullivan  @lauriesullivan, September 20, 2011

Google released a slew of features for Google+ Tuesday. While the company has opened the site to "+everyone," no invitation required, the most critical tool rolled out belongs to search marketers. It comes just days prior to Facebook's rumored announcements during its F8 Developer Conference, which takes place later this week.

Although there is no sign yet of paid-search ads in Google+, search marketers should view the search improvements in the social site as a precursor to Google launching a series of advertising tools for businesses. The release should also catch the attention of search engine optimization professionals that will try to improve search rankings.

Bringing its expertise in search to Google+, entering keywords in the search query box now returns more relevant results geared toward people and posts, as well as content from around the Web. The queries focus on content from text to photos to videos, so updates on publicly available family events are as easy to find as international news.

Search marketers should see these improvements as a step to launching advertising services and support for Google's estimated 1 billion items shared and received daily on Google+.

Aside from sharing content, users share ideas face to face. The company added Handouts on mobile phones supported by Android 2.3+ devices with front-facing cameras. The app becomes available in the Android Market today. Apple iOS support will come soon. Hangouts on Air have also rolled out. While the feature starts as a "normal" Hangout, allowing up to nine others to join, now others can watch the broadcast too.

The latest Hangouts features also provide the ability to share screens, Google documents and when users want to join or create a public hangout about a certain topic, such as music or sports.

The Google+ team also announced the launch of the Google+ Hangouts API for developers. This application programming interface, or API, initially becomes available as a Developer Preview.

For mobile, there is improved SMS support. Users in the U.S. and India can now post to Google+, receive notifications, and respond to group messages via SMS. To start texting, just verify the phone number in Google+ settings. The site also offers improved +mentions support. To add someone in a circle to a conversation, users can now +[their name] inside a post or comment. When reading a great comment in the Stream, users can now +1 it directly from your iOS device, with this feature in Android coming soon.

Given the emphasis on sharing and communicating, Google+ has also added the ability to edit profile photos and customize notifications, and has renamed Huddle to Messenger.