Adafruit HUZZAH CC3000 WiFi Shield is a CC3000 based wifi shield with onboard antenna. The microcontroller friendly WiFi modules produced so far were too slow, or too difficult to use, or required signing an NDA, or had limited functionality, or too expensive, or too large, but CC3000 hits that sweet spot of usability, price and capability. It uses SPI for communication (not UART!) so you can push data as fast as you want or as slow as you want. It has a proper interrupt system with IRQ pin so you can have asynchronous connections. It supports 802.11b/g, open/WEP/WPA/WPA2 security, TKIP & AES. A built in TCP/IP stack with a "BSD socket" interface. TCP and UDP in both client and server mode, up to 4 concurrent sockets. It does not support "AP" mode, it can connect to an access point but it cannot be an access point.
The module is carefully wrapped while Adafruit HUZZAH CC3000 WiFi Shield is produced. The shield also has a microSD socket and a reset button. It has an onboard 3.3V regulator that can handle the 350mA peak current, and a level shifter to allow 3 or 5V logic level. The antenna layout is identical to TI's suggested layout and we're using the same components, trace arrangement, and antenna so the board maintains its FCC emitter compliance. Even though it's got an onboard antenna the range is very good, as good as a smartphone's.
Adafruit Web Site