Google Plus has just released it’s app for iPhone 4/3GS/3G, but not the iPod Touch yet. It’s already been available on the Android platform since it’s release. The app works similarly to the Facebook app where you have a central hub for all of Google+ items: Stream, Huddle, Photos, Circles, and Profile.
In your Stream you can comment or +1 the post. It also allows you to easily get to your Inbox, Circles and what’s Nearby if you allow it to use your location.
The cool thing that Google Plus offers that Facebook doesn’t is the ability to limit who you post to right from the screen with a click of a button (Facebook has the “lists” feature but it doesn’t allow you to use it via the mobile app).
You can also upload multiple photos (which you can’t currently do on Facebook mobile). Here are some screen shots of the Google + iPhone App, now available in the iTunes app store.