I couldn't resist and connected one of my bluetooth modules ( Bluetooth Mate Silver to be precise ) to the digital I/Os D10 and D11 on the Arduino bit. I searched for an Android app where I could define the graphical interface by myself.
Among some others I found "RemoteXY" to be quite useful. I'm not saying that's the best and the drawback is that it's not for free. The positive aspect is that you edit your graphical interface in a web browser, which is a little bit more convenient than doing it on the tablet itself.
The concept is very interesting as the configuration is stored in the Arduino sketch and not in the app on the Android system and is transfered from Arduino to Android at connect. The interesting point is, that you can have several different systems based on littlebits Arduino and will configure the GUI depending on this particular system. There is only ONE application on the tablet or phone.
There has been a link between RemoteXY and littleBits in the past already. "The AirBoard" is an Arduino compatible microcontroller board which can be extended with some wireless boards like XBee, Bluetooth or WiFi. They also had designed a "sketchBit" to connect their AirBoard to the littleBits universe. And AirBoard uses RemoteXY for the Bluetooth connectivity and Blynk for WiFi.
Coming back to my project, I could successfully make the connection between littleBits Arduino, Bluetooth and Android. And I think it should be possible to use the IO8 and D6 signal instead to connect the Bluetooth module. I will prepare a project page to share my experiences.