As somebody who is basically face-blind, I've been wanting a face-recognizing, Facebook-enabled implant (or heads-up display, or whatever) for years. It'd be particularly handy at conferences. I mainly just want it to tell me whether I've met somebody or not, and, if I have, where and when the meeting took place and what the other person had been wearing at the time ("blue shirt", etc.). That's usually enough to jog my memory.
Really, the only major thing keeping this from being at least mostly feasible today is the lack of a good way to do the user interface. Glasses-mounted HUDs don't seem to be production-ready yet. I guess if I were one of those people that always wore a Bluetooth earpiece, I could just route it through that, but I want something a little (ok, a lot) more subtle.
By the same token, a pen and paper day planner that you carry around also makes you a cyborg, as you are delegating part of your memory functions to it.
As far as I understand http://en.wikipedia.org/wiki/Cybernetics , the planner must be able to actively communicate to you before carrying it makes you a "cybernetic organism".
But, like all other definitions it can look useless when stretched to technically apply to specific situations (like the laptop-on-back example).
For instance, my refrigerator is technically interactive by the definition of reactive interactivity: "A message is related to one immediately previous message", where my messages consist of opening and closing the door, and the refrigerator's messages consist of turning on or off the interior light.
Saying my refrigerator is interactive is technically correct, but useless and silly. Still, the definition for reactive interactivity is useful and popular (at least in computer science).
I don't think that the idea of carrying a laptop making you a cyborg is any more of a stretch than the idea of carrying a smartphone making you one. Laptops and smartphones are similar in capability, mobility and proximity (given the laptop/backpack example) and certainly in interactivity.
I am curious what it is that qualifies a smartphone as an "exobrain" that also disqualifies a laptop?
As is so frequently the case, it's all a matter of definitions. While "a cyborg has unremovable implants in the body" certainly has a long pedigree, it's arguably less interesting in practice than "a cyborg is a person whose brain has adapted to using artificial intelligent tools as an extension of itself". (Note I don't mean "tools with AI" in the usual sense, just tools that themselves bring some intelligence to the party, however limited it may yet be.)
Neither is "right" or "wrong"; they're both just definitions.
He more broadly introduced the idea of Tools as Prostheses. Telephones can be considered prosthetic ears: they can extend your power of hearing across continents. Ships can be considered prosthetic feet, they extend your power of travel, etc.
"Man has, as it were, become a kind of prosthetic God. When he puts on all his auxiliary organs he is truly magnificent; but those organs have not grown on to him and they still give him much trouble at times. ... Future ages will bring with them new and possibly unimaginably great advances in this field of civilization and will increase man's likeness to God still more."
PG wrote in How to do Philosophy:
"Wittgenstein is popularly credited with the idea that most philosophical controversies are due to confusions over language."
Here the author fiddles with the word 'cyborg', bending its definition in a fruitless philosophical argument that benefits us not and humors most of us not.
I always thought of a cyborg as having organic parts replaced with mechanical ones. So, people with prosthetics or cochlear implants would be cyborgs, but simply augmenting your brain wouldn't count.
But a cellphone would be like connecting a DVD player up to a TV with composite cables, whereas an ideal cyborg would have something akin to an integrated harddrive and video processor inside the tv.
For full description of the origination of the term 'cyber', check out Dark Hero of the Information Age about Norbert Weiner. Cybernetics means 'steersmanship'.