You seem to be drawing a line between mobile and wearable based on where the computing resource resides. [1] But no-one really cares where the computing resource resides. And cloud computing seems poised to render that distinction largely moot anyway.

When most people draw a line between desktops and mobiles and wearables, they're talking about the interface and app model. That's why netbooks get lumped in with desktops and tablets get lumped in with mobiles, despite being essentially equivalent in size and mobility.

[1] "Is the computer on my desk, or in my bag, or in my pocket, or on my belt?" vs "Do I sit at a desk with a keyboard/pointer and manipulate many apps, or do I use it pretty much anywhere with a single app in focus, or do I use it by virtue of wearing it with some new app model that fits wearable use cases?"

The best case for Google ads on a wearable would be for them to use AR to replace existing ads... look at a billboard, instead of seeing the ad on it, see a different one there. Google then effectively gets to "tax" all advertising (the ad campaign buying the billboard now needs to pay Google to let it through), and we don't have any more ads than before, just different ones.

Why replace the places where people have thought to place ads when so much of the world is empty of ads and has plenty of space?

> We already have wearable computers, but we call them "smartphones".

Smartphones are not wearable computers. I don't wear mine, but always have it with me in my pocket. I don't wear my wallet - it's in my pocket. (Laptops are also not wearable computers, even though I always have it with me.)

Do you wear your belt, or is it just always with you, hooked through some loops on your pants?

This isn't meant sarcastically -- the idea of "wearing" something is pretty tied up with the context of the object (e.g. is it "clothing") and less to do with how you're actually carrying it around, which can make "wearable" computing something of an oxymoron depending on how it's interpreted.

Whether or not the two things are equivalent in one way ("you have it with you") isn't what we're discussing. Am I wearing this book in my hand? No I am not. The ring on my finger? Yes. "Wearable" is a word that means a specific thing. It doesn't mean "something you have with you".

Right. So why are you wearing your belt (hooked through some fabric loops on your pants) and you're not wearing your phone (resting in a fabric pouch on your pants)?

No, but unlike a book, I can clip my phone to my belt (well, if it were 10 years ago and I still thought that didn't look terrible). Given Bluetooth and PANs, there's just not much different between what's in my pocket and what's on my belt.

Perhaps a distinction can be drawn based on how you use the device - with exception of audio and vibration notifications, phones have to be in your hand to be used. Wearables can be used without overly impeding whatever you're doing.

Still, having an always-accessible computing platform and internet terminal, even if it has to be held, is a pretty big deal :)

In your pocket is close enough for almost all purposes. Laptops that you have to carry are qualitatively different.

Use a strap like they do with iPods for joggers, you are now wearing your computer. I think the point is the smartphone can be considered "wearable" simply because you can, not because people already do.