iPhone. Although the site isn’t completely publicly accessible yet and still requires an invite for access, users who are privy to passing the Google+ invite red tape can now more easily access the sites from their mobile devices.

The Google+ for Android app was launched on the same day as the social networking service itself, and has been downloaded somewhere between 1 million and 5 million times since then, according to Android Market estimates. Meanwhile, Google+ for the iPhone launched on July 19, with an update already being issued for the bug-laden mobile app.

Both mobile editions feature Huddle, which allows users to send super-fast messages to their friends, as well as Instant Upload for putting photos and videos into a private album in the cloud. There are also features like Circles and Stream, which is similar to a Facebook newsfeed.

Support issues for iOS version

PCMag noted that Google+ for iOS lacks support for iOS 5 as well as administrative controls in the group chat Huddle, problems that have not been noted with the earlier Android edition. Additionally, Mashable said Google+ has been crashing in iOS 4 at a regular frequency for some users. Punit Soni, lead product manager for Google+ Mobile, said the problems will be addressed in upcoming updates.

Since Google+ and its various mobile incarnations are still in the very early beta stages, they will undoubtedly experience countless reformations in the near future. This could give the iPhone version a chance to catch up to and perhaps surpass its Android counterpart.

Continued front in the Apple vs. Google war

While Google obviously has an interest in seeing its social network available to millions of iOS users, lagging support issues and inaccessible features are ways for Google to tweak its main rival in Apple. Google-developed apps generally perform better on Android devices – particularly tablets like the Motorola Xoom.

It bears watching whether the performance spread of Google+ between Android and iOS devices (not to mention other mobile platforms like Windows Phone 7, BlackBerry and WebOS) continues to widen. Of course, the best way for the app to talk off and truly compete with Facebook, Twitter and other social networks is to ensure that it is a compelling and reliable experience for as many users as possible.

Stay tuned.