There's a lot to like about Google Plus, the new social network from everyone's favorite search engine: the design, the thoughtfully created and easy-to-use privacy settings (Circles), the built in mobile chatting (Huddles) and video chatting (Hangouts) features, the smart news reader (Sparks), and more. But if Google Plus had one "killer" feature, it would definitely be the instant photo uploads from Android.

Why is this? Because it's the one feature that will actually encourage adoption.

Cloning Facebook Isn't Enough

In many ways, Google Plus is a Facebook-inspired clone. Google hasn't rethought social so much as re-engineered it. You can almost visualize the checklist that went into the social network's creation. Do we have a like button? Check! (It's the+1 button.) Do we have a News Feed? Check! (It's the "Stream.") Do we have privacy settings? Check! (They're called Circles.)

That's not to say that Google hasn't done a great job with the implementation. Google Plus is already a much better product than the half-baked experiment that was Google Buzz, the mashed-up social networking aggregator that was smooshed into your Gmail inbox.

But for the mainstream user, a Facebook-like experience isn't necessarily enough of a draw to lure them away from a social network where their friends already hang out, to a new one populated with their email contacts, no matter how pretty it looks.

Unless, there's a reason. And in Google Plus's case, that reason is photos.

Android is Google Plus's Secret Weapon

There are now half a million Android phones activated each dayAs of May 2011, there were over 100 million Android devices worldwide. Consider this Google Plus's potential install base.

And what's the key to social networking success? Photos. Facebook, if anything, is simply the world's largest online photo sharing service. All those status updates and Farmville sessions are just icing on the cake. This summer, Facebook is expected to cross the 100 billion photos mark, which is an impressive statistic, to be sure. However, Facebook still struggles on the mobile front, and even more so on Android, which is less developed than its iPhone counterpart.

Have you ever tried uploading a group of photos to Facebook from your phone using the native app's uploader? Isn't it fun to upload pictures one-by-one to albums you have to first create and name? Oh, it's not?

Well, don't worry then, Google has you covered.

While much of what Google offers feels like a Facebook alternative, the Android application is Plus's real innovation. With an opt-in feature called "Instant Uploads," your mobile phone's photos are immediately online, and are, by default, private only to you. Later, you can visit you that private album's page, and reshare individual photos with the appropriate group. Baby photos? Maybe just share with family and/or close friends. Photos of a beautiful scenic view you took on your nature walk? Share with everyone. And so on. You decide.

"Unlimited" Photos Beats iCloud's PhotoStream Limit of 1,000, & Share by Email is Easier than on Facebook

This photo-sharing idea in Google Plus isn't so different, really, than what Apple is introducing with iCloud. Via iCloud's PhotoStream service, your mobile photos are synced to all your devices instantly: computer, mobile. "cloud" (Apple's servers). But iCloud has an Achilles' Heel: if you don't manually move those photos into photo albums on your Mac or PC, they'll eventually disappear. iCloud, you see, only stores the last 1,000 images in the "cloud."

Google Plus, however, will store them all, forever. (Or at least for as long as Google exists.)

Out of everything that Google has launched, this one feature stands out as having the potential for the most disruption and the most viral impact, not only because of this instant upload and free cloud storage, but also because of the "share by email" feature. That's right: your "friends" don't have to be on Google Plus before you initiate the sharing process.

Unfortunately, this feature is currently broken. The recipient receives a confusing "we're working out the kinks email" instead.

Of course, we should give credit where credit is due. Share by email isn't a Google innovation, but the implementation is much better. For example, Facebook has a similar option, but it's tucked away at the bottom of your photo album, practically hidden from view.

For Google, share by email makes sense. After all, Google has your Gmail address book on hand, and can easily auto-complete email addresses for you, even if you don't want to use the friend lists known as "Circles."

And if you wanted to, you could even choose to just use Google Plus to share photos via email or with your Circles, while ignoring its other Facebook-like features like the News Feed...err...Stream, and chat. Of course, once you get comfortable with Photos, you might venture out and give those other things a shot, too. Hey, that's not a bad plan, Google.