This Adafruit Bluefruit LE (Bluetooth Smart, Bluetooth Low Energy, Bluetooth 4.0) nRF8001 Breakout allows you to establish an easy to use wireless link between your Arduino and any compatible iOS or Android (4.3+) device. It works by simulating a UART device beneath the surface, sending ASCII data back and forth between the devices, letting you decide what data to send and what to do with it on either end of the connection.
Unlike classic Bluetooth, BLE has no big contracts to sign and no major hoops that you have to jump through to create iOS peripherals that you can legally design and distribute in the App Store, which makes it a great choice compared to classic Bluetooth which had (and still has) a lot of restrictions around it on the iOS platform.
And now that Android also officially supports Bluetooth Low Energy (as of Android 4.3), it's also -- finally! -- a universal communication channel covering the main mobile operating systems people are using today.
We can get you started super fast with this BLE module which can act like an 'every day' UART data link (with an RX and TX characteristic). Send and receive data up to 10 meters away, from your Arduino to an iOS device. Adafruit have even made it easy to get started with their very own BLE connect app that has a "serial console" for sending/receiving data and also an 'arduino pin i/o control station" to let you set pins on your Arduino to inputs or outputs, high or low logic or even PWM output, as well as read button presses and analog inputs. You can start prototyping your accessory and then use Adafruit open source Objective C code to base your new app on!
The nRF8001 is nice in that it is just a BLE 'peripheral' (client) front-end, so you can use any micrcontroller with SPI to drive it. We have example C++ code for Arduino, which you can port to any other microcontroller, but some microcontroller is required - it is not a stand-alone module!
Please note: There is not an Android version of the Adafruit Bluefruit LE App available (our native BLE application) at this time,however you can use Nordic's Android nRF UART application with the nRF8001 Breakout on BLE capable Android devices (Nexus 4, Nexus 5, Nexus 7, etc.) for sending/receiving data. This is a product for ADVANCED USERS - At this time we recommend this product for people who are either OK with using the apps available (Nordic's UART demo or our Bluefruit LE Connect) or are comfortable with writing iOS apps (and can refer to our App repository). We do not have a tutorial for writing your own iOS or Android BLE app at this time, don't worry we're working on one :)
There is a guide to help you setup your nRF8001 Bluetooth Low Energy breakout, and start using some of the sample sketches we provide with it to connect to an iOS or Android device. If you're new to Bluetooth Low Energy, be sure to check out Adafruit Introduction to Bluetooth Low Energy learning guide as well!