I've not seen one, but I'm not overly impressed; it strikes me as being a marketing person's solution to the problem, rather than the engineer's. I keep heaps of other stuff in my bag as well: papers, tickets, etc. when I'm travelling, and I can forsee issues when I plug my laptop into the bag during a presentation, and I need something from my bag.
Laptop power supplies need to have another three or so outputs on them, each switchable for output voltage, amperage and polarity, and you just buy cables that can plug into that common interface. Of course, marketing dweebs could never work out how to use this ...
And of course many devices are now starting to use the USB port as a recharging source; this is a reasonably good alternative too.