Google's sixth annual conference for software developers opened Wednesday with a chance for the company to showcase its latest services. Announcements include a new phone, new tools for online games and a music-streaming service that will allow Android users to listen to their favorite songs and artists for a monthly fee.

The audience of about 6,000 people at "Google I/O" includes engineers and entrepreneurs who develop applications and other features that can make smartphones and tablets more appealing. Reporters from around the world also will be on hand, giving Google a chance to generate more hoopla about its latest innovations.

Android already has been activated on 900 million devices made by Samsung Electronics Co., HTC Corp. and other manufacturers. Android devices are the chief rivals to Apple's iPhones and iPads. Android has helped Google make more money because its search engine and other services, including maps, are usually built into the devices. That tie-in drives more visitors to Google and gives the Mountain View, Calif., company more opportunities to sell ads.

Much of the speculation about the conference has centered on a possible upgrade to the Nexus 7, a mini-tablet that debuted at last year's event.

Google also may provide more insights into the popularity of Google Plus, a social networking alternative to Facebook that launched nearly two years ago. In an attempt persuade more people to use Google Plus more frequently, Google has promised to keep adding tools that aren't available on Facebook.

Google's conference was being held at the Moscone Center in San Francisco.

The keynote kicked off at about 9 a.m. PDT and was expected to last nearly three hours. The conference goes through Friday.