First, the bad news: there's no native iPad app for Google+ yet. However, Google is rolling out a new interface for its mobile web apps that is closely modeled off the native apps for iOS and Android, which means this will probably be the primary way iPad users interact with the service for the time being. The main part of this new interface (designed for iOS, Android and BlackBerry 7) is the streams area, which lets you easily swipe between a full timeline of posts from people in your circles, public posts from those nearby, and trending "what's hot" posts.
Unfortunately you're unable to customize the different swipe-able columns — unlike in the native apps, which let you add and swipe between as many different circles as you want, you're stuck with the three default options. You can still see streams from your individual circles on the web app, you just can't set up easy access to those that you view the most. There's also no way to upload photos through the web app (or instantly upload pics you take), which means all those images you shoot using the new iPad's camera won't be shared quite so easily. While this new interface is an overall improvement on what came before, we imagine most iPhone and Android users will stick with the free native apps. For iPad users, though, it's a better experience than what came before... but a native app would be even better.