Pictures of the dock port:
Pictures of the plug that fits it. It's the same 30-pin plug as found on the iPod and a bunch of other devices.
(Last 3 images from https://www.sparkfun.com/products/8295)
What I just ordered to work on this project:
(Again from https://www.sparkfun.com/products/8295)
Here's what I've figured out so far.
The cable from my iPod Nano 6th gen has pins 1, 15, 16, 23, 25 and 27. All others are missing. I haven't had time to analyze it all yet, but according to allpinouts.org, 1 is a ground, 15 and 16 are grounds and are tied together (internally on the iPod motherboard), 23 is USB +5v, and 25/27 are USB Data+/- OR, alternately, they are resistor-to-ground value-based signals.
My theory so far is that there is some internal resistance between the pins in this cable and other pins or ground; because plugging just the cable in--with it not being plugged into the USB port--disables the Blu's touchscreen and automatic screen rotation features and locks the screen in whatever position it's in when you plug in the cable. (Although interestingly, if you plug it in in landscape mode, you can use the screen rotation lock hardware button to put it back to portrait mode.) Plugging the other end of the cable into a USB port brings up the Recent Apps display (the thing that comes up when you hold the touchscreen home button down) and the phone says it's charging, but the touchscreen is still disabled. Not sure if it's actually charging or not; I'm gonna leave it plugged in for awhile and see. The phone does not show up as a new USB device when this (iPod) cable is plugged into the dock port.
Once I get the breakout board I'm gonna take the phone apart and see if I can trace where the pins in this dock port go. I'm also going to wire up a USB cable to the breakout board and see if I can get the phone to enumerate.
Hopefully I never toast my phone.
Edit for more pics from teardown:
Notice that this ribbon cable is 3 layers; those are little pieces of a paperclip holding them apart to show the layers.