For those of you wondering where the iOS app is for Google+ is, you may finally have an answer, albeit a vague one.
It appears as though the Google+ iOS app has been submitted to the App Store, sometime prior to yesterday, and is currently awaiting approval, according to a Mountain View employee via her own Google+ account. This should be good news for those of you worrying Google would limit Google+ to only having an app for it's own in-house Android operating system, as one was available upon Google+'s launch.
There has been no word from Apple when the Google+ iOS app will appear in the App Store. This isn't out of the ordinary, as Apple screens all apps submitted to them before ultimately approving well over 90% of them. There should be little concern about any holdups, and you should see a Google+ in the App Store fairly soon.