• by Laurie Sullivan , Staff Writer @lauriesullivan, February 13, 2012

The number of people signing up on Google+ isn't an accurate measurement of active users similar to metrics such as time spent on-site, according to Josh Bernoff, SVP of idea development at Forrester Research. He wants to see statistics related to activities and the length of time spent with an application or feature before he labels the social network as successful.

Google began revealing a product road map last week as it slowly rolls out features to keep the buzz buzzing and adoption growing past the 90,000 members that co-founder Larry Page announced during the most resent earnings call.

Google+ captured 20 million unique visitors in December -- about half of Twitter's 40 million, according to Compete. The data firm estimates 50 million visits and 200 million page views on Google+ for that month, pointing to unique visitors as a good metric of popularity, and visits as a good measurement of loyalty.

With a 1% sample size for the U.S., Compete’s panel of 2 million Americans measures a Web site's popularity for non-mobile U.S,-based users. On mobile, Google+ gains its momentum from more than 700,000 Android-powered smartphones activated daily, which include complimentary Google+ accounts.

Expect to see more integration of Google+ into other Google products, according to Google+ Engineering Director David Glazer, who provides some insight into the social network's road map. He said today that APIs for features like Games are invitation-only, and there is no publicly available API for Hangouts -- but that will change as Google better understands how users interact with the site and features.

Glazer also said to expect APIs for location and identity on mobile device platforms. The company is looking into numerous channels and new ad formats for apps to help companies use advertising dollars to reach their audience, such as applications on brand pages -- although the company has not put this request into the development queue.

The focus remains on getting Google+ users to share content, comment on posts and talk with brands. Games prompt people to "engage" not only with each another, but with brands.

A bit geeky, but the Google Developers' team holds weekly updates in a Google+ Hangout. Last week the group invited developers from the Google+ developer community to join in the discussion. Google engineers responded to questions and comments about the Google+ platform. Notice the Apple laptops used by Jonathan Beri and Wolff Dobson.