There’s a new version available: v2013.12.18.121.  This version contains a few bug fixes around the Arduino, and the news feed is working correctly again.

There is new Arduino code available which you can download and then upload into your Arduino.  This new code fixes a problem with the Arduino’s digital input, as well as making the Arduino/Experimentor communication more robust.  Additionally, the new Arduino code ensures that analog inputs will always report when they hit 1023 – the Arduino’s maximum analog value; previously they might not report 1023 if the Arduino first sees something close to that, like 1020.

Finally, one of the more important fixes for the Arduino is that you can no longer use pins 0 or 1, and attempting to do so will report an error within Experimentor.  Pins 0 and 1 are used by Experimentor to communicate to and from the Arduino to control the Arduino and to receive data from the Arduino over the USB port.  So it’s very important that these pins are not used for devices.

I hope that helps!