It's screwed together, so probably one unit. According to Anandtech, the screws that normally hold up the bottom plate of the laptop are removed (though there'

It's screwed together, so probably one unit. According to Anandtech, the screws that normally hold up the bottom plate of the laptop are removed (though there's no need to disassemble the device entirely) and this would then include longer screws to hold the assembly together. As far as charging goes, my Asus Transformer tablet has a potentially similar charge mechanism. The tablet plugs into the keyboard base using the charge port, and then plugging the charger into the keyboard base charges both the tablet and the keyboard. It uses the keyboard base battery before using the tablet battery. You'd just charge this unit only; no complicated charge information software necessary. If it's plugged in, charge it and the Macbook, if it's not, charge the Macbook with the onboard battery, or if it's discharged, stop charging and use the Macbook battery. I imagine that removal of the bridge dongle would help convince the TSA that it's two batteries.