The whole rig requires an Arduino board, and it's not exactly for Mom to do on her own (unless of course your Mom is an electrical engineer, which is entirely possible), because it also will walk you through making your own moisture sensor. Once you've got everything plugged in, the Arduino software will talk to the unit via USB and ethernet, and a terminal script will actually send the Tweets out. Unfortunately, despite a quick search on Twitter, I wasn't able to find any plants actually tweeting, but if you have one, let us know.
