This question arose from the comments page of The Nifty Minidrive's Kickstarter page
The Nifty Minidrive is essentially a microSD card adapter that fits perfectly into the SD-slot of the MacBook Pro / Pro Retina / Air so that a microSD card can be used as additional storage.
However a backer came across this apple support document which explains that for a Mac to be able to enter Standby mode one criterium is that it must "Have no SD card inserted".
This is a potential deal breaker for many backers.
Is there a way to enable deep sleep mode even though an SD card is inserted?
(I have no way of actually testing this, but does an inserted SD card which isn't mounted prevent deep sleep as well? If it doesn't it should be possible to make a script that unmounts the SD card before the Mac goes to sleep and mounts it when it awakens?)