The Arduino prototyping standard has been around for about 6 years now, and has proven to be immensely useful for sensing devices. It's the heart of the DustDuino and many other sensor nodes.
But for all the flexibility that the Arduino provides for collecting data about the environment, there still isn't a reasonably-priced, reliable shield to send data via WiFi.
The official Arduino WiFi shield, while well-supported, costs around $85. That's a pretty high price to connect a $4.50 chip to a network. Cheaper options such as the WiFly shield do exist, but some of the libraries supporting these devices are difficult to decipher or unstable, if they exist at all.
I spent a long time myself looking for a cheap, effective WiFi solution for the Arduino platform, and I've been very pleased with the $35 RN-XV module.
