Playing the part of the Raspberry Pi B+ this evening will be... an ordinary model B. Don't worry, we can still prove the concept.
Here we see a 26 pin stacking header along side a 14 pin stacking header. The one on the left is sold by AdaFruit, and it's what I've been using for my Pi Power prototypes. I believe they actually come from 4uconnector.
The 14 pin stacking header on the right is actually the remains of a 26 pin header that was cut down with a dremel. That's why the one edge looks a little... raw. Don't worry, that edge doesn't matter either - we'll put that edge on the outside.
Our hero - Pi Power!
In this photo, we're going to pretend that we've attached Pi Power to the 40 pin GPIO header of a B+ Pi. You can see that the GPIO header on the board has 7 rows that continue on at the end of the first 13.
This is something you can't do with a ribbon cable connector. Ribbon cable connectors - also known as IDCs - are wider than PC mount headers - you can't use a narrow one on a wide header because the wide edge of the connector will hit the first unused row of pins. But as you can see, Pi Power has no problem fitting properly.
This points out that Pi Power can be used as a serviceable workaround for 26 pin IDC cables! You can use Pi Power both as an IDC cable adapter and as a power source!
Here's another view of the same thing. You can see that Pi Power hangs way off to the right - on a real B+, that space would be the rest of the first 26 pins of the GPIO header, but for this photo shoot, we shoved it over to the right by 7 rows.
If you want to use Pi Power and the bottom 7 rows of GPIO pins, then all you need to do is add a 14 pin stacking DIP header onto the GPIO connector right next to Pi Power. Now all 40 pins are at the same level, and you can plug anything you like in while Pi Power supplies power to everything.
Just to prove that you can plug something in, this 26 pin stacking header is pretending that it's a 40 pin header. This works whether the header you're attaching is IDC or PC mount. Of course, it won't accept a 26 pin IDC cable, but you can still make that work by simply removing the 14 pin stacking header first.