New data from Experian Hitwise show a dramatic increase in traffic over the week since the service opened to everyone. Visits to Google Plus increased by 1269% last week. The site received 15 million U.S. visits, up from 1.1 million the week before. Google Plus went from ranking 54th in Hitwise's Social Networking and Forums category to ranking 8th in just one week.

That's not all the traffic, either. These stats don't include mobile users or visits from the ubiquitous black Google toolbar. The data still show that Google Plus is disproportionately comprised of "influencers" and "early adopters" compared to other social networks, but the removal of invitations seems to have jump-started visits to the service. According to Paul Allen's estimates, which have been on track in the past, Google Plus currently has around 43 million users.

Facebook's changes announced last week drowned out the news of all of the new features on Google Plus, but Google is timing its announcements carefully. Along with the announcement that the service was open to all, it launched a bunch of new features, but they were mostly for power users - the kinds of users who would use Google Docs in a video chat.

Google then let Facebook have its fun at its f8 conference, waiting until today to launch CityVille, one of Zynga's most popular Facebook games and clearly a play to attract more mainstream users. The major growth in traffic announced today restores some of Google Plus' standing in the tech press, who have been all aflutter about Facebook since f8.

The Google Plus team also announced today that users can now share their circles, an anticipated feature that will help users discover new and interesting people to follow on Plus.

Have you been using Google Plus more since its announcements last week? Let us know in the comments.