"It's too early to tell but ... if Facebook isn't careful, they could drive renewed growth to Google+, and may have already," he added.

However, it's doubtful that Google+ can't thrive on Facebook castoffs alone.

Brad Shimmin, an analyst with CurrentAnalysis, said the coming months will be a strong indicator of how popular Google+ will be - especially once the hoopla of the site's opening cools off.

"Signups are one thing," said Shimmin. "Usage is another. I think only time will tell for Google+ in terms of its ability to truly compete with Twitter and Facebook in user retention and day-to-day usage. I think Google+ holds the most promise not as a rival to Facebook but as an enterprise social networking platform."

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at , or subscribe to . Her e-mail address is .