New Arduino supports WiFi and is based on the Arduino Leonardo including two processors - one for running the Arduino code, and a separate system on a chip used for the WiFi. The WiFi side runes a variant of OpenWRT and additional APIs are provided for connection to email, twitter, facebook, foursquare and facebook. It also supports uploading new firmware to the Arduino side over WiFI (the new Arduino IDE scans fo any devices in the area to allow connection and upload).
This would be great for putting sensors around the house and you don't have to run wires everywhere. I am a bit skeptical of the security of the device if the new IDE scans for all devices and you only need a password to reprogram it. I am sure someone will find a flaw in the password scheme over time, so I would be careful not to use it to unlock the doors in my house or control the security system.