Adafruit is currently shipping R3 of the Arduino Uno
Includes the Thru-hole (THM) type Arduino Uno R3. The new Uno is the latest version after the Duemilanove, with an improved USB interface chip. Like the Duemilanove, it not only has an expanded shield header with a 3.3V reference and a RESET pin (which solves the problem of how to get to the RESET pin in a shield) AND a 500mA fuse to protect your computer's USB port, but ALSO an automatic circuit to select USB or DC power without a jumper! The Uno is pin and code-compatible with the Duemilanove, Diecimilla and older Arduinos so all your shields, libraries, code will still work. The new R3 (3rd revision) of the UNO has a few minor updates, with an upgrade to the USB interface chip and additional breakouts for the i2c pins and an IORef pin. For more information about the UNO, the R3 and what the updates mean, please check our UNO FAQ!
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