After some curiosity about RS232 serial communications, Guillaume Dallaire investigated further and started experimenting with RS485. This standard allows more than one device to communicate with a host (such as an Arduino) such as sensors or display devices. That is in fact what Guillaume has demonstrated, and apart from demonstrating the required hardware and RS485 interface ICs he also offers simple code to demonstrate the system.
You can see how simple it is to implement RS485, and one of the main reasons to use it is you can have a distance of over one hundred meters between devices - much longer than SPI or I2C. To find out more, check out his project page. And for more, we're on twitter and Google+, so follow us for news and product updates as well.