It uses an Electric Imp, an Adafruit Wave shield and an Arduino Uno
The Electric Imp enables you to quickly connect devices (including arduinos) to the internet through your Wifi network.
The Adafruit Wave shield makes it simple to play audio files from an SD card using an arduino.
When I first came across the Electric Imp I started wondering how I could combine it with an Arduino and make a fun remotely activated project. At around the same time I was also tinkering with the Adafruit wave shield and realised they'd make perfect companions.
In the end I decided to record myself saying a few different messages such as "I'm on my way home - get the kettle on!" so that I could trigger the messages as I left work. I figured this would be much more fun than the usual text message.
I built my "Imp-ersonator" into a photo frame in the living room so that I can trigger a message to be heard by whoever's at home when I'm leaving work (usually my wife or children but it occasionally freaks out visiting friends which is an added benefit...)
To build your own you'll need the following things:
1) Electric Imp Card
2) Electric Imp Shield for Arduino
3) a few jumper wires
4) Arduino Uno
5) Adafruit Wave Shield
6) 8 Ohm Speaker
7) soldering kit (solder, soldering iron, etc)
8) USB cable (A-B) for uploading code to the arduino
9) Photo frame that is deep enough to fit everything in