Actually two wires: data and ground, but the 1-Wire protocol is still quite minimalistic and ideal for communication with sensors, as implemented in e.g. digital temperature sensors like the DS18B20 that actually looks like a transistor (3 pins and all) but is actually a small “temperature computer”. The protocol would also be very useful for alarm sensors and such.
A drawback (and in my opinion a fundamental design flaw) is that the timing of the communication is very critical, so a slower “managed” platform like .NET Micro Framework might have trouble achieving such timing accuracy. The protocol should simply have been combining data and clock and relied on a pure host-slave setup.
Anyhow, I’m currently trying to get one of those temperature sensors to work with a Netduino, and it’s not all easy. There’s supposedly a prototype implementation of 1-Wire in the Netduino system code, so I’ll try with that.