At this weekend's Maker Faire, Arduino released the new Arduino Yún. This new board features on-board Wi-Fi meaning you'll no longer have to rely on expensive shields or clones to have Wi-Fi in future prototyping boards. This is great news as Wi-Fi shields were often as expensive, or more so, than the Arduino itself.
Interestingly enough, the new Arduion Yún utilizes both Linux and Arduino. Wi-Fi is handled by a small Linux-powered chip that takes care of sending and receiving HTTP. The Arduino side of things acts as normal. One of the major benefits from this is the ability to reprogram the Arduino via Wi-Fi, no USB required.
The board will set you back an estimated $69 and should start shipping at the end of June.