Google+ has gained tremendous traction since its launch late last month. It took barely two weeks to top 10 million users, despite the network being invitation-only since it was (and is) in field test mode. Until the other day, one thing's been missing was an iPhone / iPod Touch app. The Google+ network was accessible by iOS, but its users were left out of one useful feature the Android version had: "Huddle,"a function that allows for instant messaging between groups of mobile users. That all changes with the iPhone app: Now, iPhone users will be able to update their stream, view public posts from nearby users, manage circles and participate in huddles without opening their browsers. It will be interesting to see how opening the platform to the massive iPhone user base impacts the network's growth.