If you aren't familiar with the Electric Imp, it essentially provides an easy, integrated way to connect almost any hardware device both to other devices and to internet services. It's more than just a WiFi card, or even a WiFi module with processing built in - it's an integrated platform that deals with the drudgery of connectivity, allowing you to concentrate on the application instead of the mechanics.
It does this by integrating an 802.11b/g/n WiFi transceiver, a great antenna, a Cortex-M3 core and lots of flexible I/O in a tiny package. Of course, if you're developing for it you'll need a way to get in there and poke around. The Electric Imp Breakout Board allows you to explore the capabilities of the Imp by providing standard 0.1" headers to solder to as well as the necessary CryptAuthEE IC to identify your prototype to the Imp Cloud service!
Note: If you want to use the mini-USB or battery inputs for power, you will need to populate the 3-pin jumper and set it to either 'BAT' or 'USB'. Otherwise, you can just simply power the board using VIN and GND without the use of a jumper.