Maybe others have already figured this out... but here's how I got the SD card on the Adafruit board working. Hopefully this helps w/ Nephilim's issue too.
RFduino uses GPIO 0&1 for the UART RX/TX. Since we are limited on the number of GPIO's available, we need to disable the serial connection and repurpose a GPIO for our SD_CS.
To do this you can simply comment out the Serial.begin(9600) call in the source. I also added a call to UART0_Stop() for safety.
After this change I set the SD_CS = 1 in the Adafruit bitmap example code (along with copying TFT pins from the graphics test code), wired the SD_CS pin to GPIO1, and was rewarded with a nice parrot image on the display.
This leaves GPIO0 free for whatever. (Obviously it's possible to make library modifications to enable the use of a mux/inverter/etc. to expand the number of GPIO's... but I'm not going to experiment with this.)
On an unrelated note, I found that the RFduino library has changed since I implemented my patch. It will compile with RFduino library 2.0.2 if you comment out the include of wiring_private.h near the top of Adafruit_ST7735.cpp.