There's a saying that goes something like this; to really know someone all you have to do is look at their bookshelf, check book or medicine cabinet. I say, have at it – just don't ask for my phone.

I'd grant anyone access to that other stuff before I hand over my smartphone. And with good reason: just look at the numbers. A Mary Meeker/Morgan Stanley study notes that by 2015 more people will access the Internet by phone than from a desktop. By this holiday season smartphone penetration will be at 50 percent. A year from now it's going to be 90 percent. That's incredible. No other medium has grown so quickly or become so pervasively integrated into our everyday lives as mobile.

Its no revelation to say mobile is big – and getting bigger. But it's huge for brand advertisers to grasp how quickly it is shaping human behavior because when behavior patterns change rapidly it spells massive media opportunity.

If you're in any doubt that mobile could soon rival mom consider this: a few years ago we used our phones to check the weather, now we use them to pay bills on the fly, get us through airport security and they're about to do a whole lot more.

Leave the house today and you need three things: wallet, keys and phone. By tomorrow it will be just the one. We'll use a phone to pay a restaurant bill and point it at the car to start the engine to drive home. And when Near Field Communication (NFC) kicks in, things are going to get really interesting. You'll be able to bump your phone to pay at cash registers, to check in at venues and even verify identity. That's crazy fast progress.

But cool tools and functionality aren't what is making us more dependent on the phone than the family member. And it's not the critical factor for brands to watch. The way our phones track our personal use of data is going to open up a whole new channel for personalized digital content direct to consumers' pockets.

Our phones already know more details than our moms ever will: where we are, who we are with, what we're saying to them and what we just did (possibly with photographic evidence). Tomorrow's models are going to be smarter, learning from our mobile behavior and feeding a digital experience more closely geared to our lifestyle choices and the brands we love – or who are loving us.

The latest smartphone to hit the streets – Apple's iPhone 4S –already seems like a letdown. It is as if no-type voice commands to change appointments and text contacts, or the ability to find any sushi restaurant in any urban city on earth - plus directions to get there - are now just not enough for us. With each successive product launch we will ask unbelievable things from our phones and it's the fault of people like the late, great Steve Jobs. He re-calibrated both what the humble phone can do and what we now demand.

So as customers line up to get that new iPhone and advertisers line up to target them, where will we end up? Will consumers freely accept ongoing eerily personalized prompts and content directed to them and their phones? Will brand advertisers act responsibly or see a gold rush?

Time will tell. Until then, only one thing is sure. Mobile has cut the apron strings to the desktop, left mom behind, and it's up to each of us to at least call her and make it right.