Apple has just approved the Google+ iOS app, and you can get it now! Here is the iTunes link, and the application is free of charge.
It seems quite similar to the Android app, which is a good thing. Slashgear has a good look at the app. iOS users, try it out and share your thoughts in the comments section below!
Keep in mind, this is *NOT* an iOS app, but an iPhone app. It will not work on iPads or iPod Touches.